PhD disertation themes – how to start?
Institute of Physics offers several PhD positions every year in a few doctoral degree programs. Možné témy pre štúdium nájdete nižšie. Possible topics for Your study can be found below. As a first step, it is best to contact the potential supervisor who will provide you with the most qualified answers to the topic, tasks and position requirements.
Theoretical and mathematical physics (4.1.2)
Filip, Peter: Quantum oscillations in external fields
(Kvantové oscilácie v externých poliach)
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Supervisor: Filip, Peter, Mgr., PhD.
Gendiar, Andrej: Quantum mechanics in the language of tensor networks
(Kvantová mechanika v jazyku tenzorových sietí)
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Supervisor: Gendiar, Andrej, Mgr., PhD.
Goals: Properties of tensor-network states are investigated by the entanglement entropy in quantum spin models.
Annotation: The tensor-product states (TPS) are frequently used in modern physics in order to obtain energies and eigenstates of quantum models. The typical systems to be studied are spin models whose Hamiltonians describe magnetism at zero temperature. By means of the tensor-product states, a quantum wave function (eigenstate) is approximated. The wave function contains both the physical degrees of the freedom, describing the Hilbert space, and the auxiliary (non-physical) degrees of the freedom, whose size controls range of the correlations, i.e., the accuracy. Many-body interacting spin systems are to be characterized by the TPS at the phase transition be means of the quantum entanglement. Since it is a non-trivial task, being non-analytically solvable, numerical approaches can be used, in particular, an arbitrary programming language can be freely applied, e.g., Python, MatLab, C++, etc. Novel alternative methods based on the tensor networks are to be proposed, which will originate in the renormalization techniques.
Gendiar, Andrej: Many-body effects in progressive low-dimensional materials
(Many-body effects in progressive low-dimensional materials)
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Supervisor: Gendiar, Andrej, Mgr., PhD.
Kalinay, Pavol: Dimensional reduction of evolution equations in space constrained systems
(Dimenzionálna redukcia evolučných rovníc v priestorovo obmedzených systémoch)
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Supervisor: Kalinay, Pavol, RNDr., CSc.
Plesch, Martin: Quantum computers in NISQ era
(Kvantové počítače v ére NISQ)
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Supervisor: Plesch, Martin, RNDr., PhD.
Goals: The goal of the work is developing and testing algorithms for NISQ quantum computers.
Annotation: NISQ (Noisy intermediate-scale quantum) computers are quantum computers available today that contain tens to a few hundred qubits, can execute a protocol with a depth of a few tens of steps, and are heavily influenced by errors and noise. We will develop and test algorithms applicable on such computers.
Šamaj, Ladislav: Statistical mechanics of Coulomb systems
(Štatistická mechanika coulombovských systémov)
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Supervisor: Šamaj, Ladislav, RNDr., DrSc.
Ziman, Mário: Quantum information structures in space-time
(Kvantovo-informačné štruktúry v priestoročase)
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Supervisor: Ziman, Mário, doc. Mgr., PhD.
Annotation: Recently the fields of quantum information and (loop) quantum gravity found common research interests. There is a believe the methods of quantum information theory are useful in quantum gravity. Indeed, some of the quantum gravity phenomena were already "simulated" on cloud quantum computers. The aim is to adapt the operational approach of quantum information theory for the analysis of physical principles of quantum gravity.
Ziman, Mário: Optimalisation of higher-order quantum structures
(Optimalizácia kvantových štruktúr vyššieho rádu)
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Supervisor: Ziman, Mário, doc. Mgr., PhD.
Annotation: Inevitable randomness of quantum theory manifests itself through quantum measurements. Their predicted outcome statistics is captured by Positive operator valued measures and if a description of post-measurement states is needed formalism of quantum instruments can be employed. More complex measurements can be built out of simpler ones by sequential use of the instruments or by interactions and measurements of ancillary quantum systems. The goal of this thesis is to understand potential of realizable measurements both in theoretical and in practical setting tailored for specific NISQ (noisy intermediate scale quantum) devices, such as IBM quantum experience, or other. We will therefore focus on simulability of instruments, efficient implementation of POVMs, and higher order measurements such as quantum testers.
Ziman, Mário: Quantum verification methods
(Kvantové verifikačné metódy)
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Supervisor: Ziman, Mário, doc. Mgr., PhD.
Annotation: Certification of quantum state is an example of so-called inverse problem in quantum theory. The aim is to develop statistical verification methods to certify properties of quantum devices, specifically of quantum processes. This research is important for the experimental justification of the performance of quantum technologies.
Pivoluska, Matej: Resource efficient variational quantum eigensolver using non-gradient optimization methods
(Zdrojovo efektívny variačný kvantový eigensolver využívajúci negradientové optimalizačné metódy)
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Supervisor: Pivoluska, Matej, RNDr., PhD.
Goals: The student is expected to develop novel optimization methods for variational quantum eigensolver that minimizes the number of quantum computer uses. The new method shall be compared to alternative methods existing in the literature.
Annotation: Quantum computers are expected to provide exponentially growing power thanks to their use of quantum effects and indications of so-called quantum advantage have been demonstrated. Unfortunately, the current capabilities of quantum computers are still rather limited. Currently the most promising algorithms for practical purposes seem to be hybrid algorithms [Rev. Mod. Phys. 94, 015004 (2022)], where only some part of the calculation is performed by a quantum computer. An example of such an algorithm, is the variational quantum eigensolver (VQE) [arXiv:2111.05176], which calculates the smallest eigen-value of an input matrix. Within this thesis the student is tasked to develop resource efficient methods of VQE that would allow its use in practical applications with existing quantum computers. The student will focus on non-gradient methods (e.g. Particle Swarm Optimization [Evolutionary Computation (2017) 25 (1): 1–54.], or genetic algorithms [An Introduction to Genetic Algorithms. Cambridge, MA: MIT Press. ISBN 9780585030944.]) and compare them to solutions existing in the literature e.g. [Quantum 4, 263 (2020)] and [Quantum 4, 314 (2020)].
Pivoluska, Matej: Resource efficient variational quantum eigensolver using gradient optimization methods
(Zdrojovo efektívny variačný kvantový eigensolver využívajúci gradientné optimalizačné metódy)
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Supervisor: Pivoluska, Matej, RNDr., PhD.
Goals: The student is expected to develop novel gradient-based optimization methods for variational quantum eigensolver that minimize the number of quantum computer uses. The new method shall be compared to alternative methods existing in the literature.
Annotation: Quantum computers are expected to provide exponentially growing power thanks to their use of quantum effects and indications of so-called quantum advantage have been demonstrated. Unfortunately, the current capabilities of quantum computers are still rather limited by numerous issues. Currently the most promising algorithms for practical purposes seem to be hybrid algorithms [Rev. Mod. Phys. 94, 015004 (2022)], where only some part of the calculation is performed by a quantum computer. An example of such an algorithm, is the variational quantum eigensolver (VQE) [arXiv:2111.05176], which calculates the smallest eigen-value of an input matrix. Within this thesis the student is tasked to develop resource efficient methods of VQE that would allow its use in practical applications with existing quantum computers. The student will focus on gradient methods (e.g. SPSA [Stochastic Recursive Algorithms for Optimization: Simultaneous Perturbation Methods, Springer (2013)], or MGA [Quantum Science and Technology 5 (2020) 044008]) and compare them to solutions existing in the literature e.g. [Quantum 4, 263 (2020)] and [Quantum 4, 314 (2020)].
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Physics of condensed matter and acoustics (4.1.3)
Butvinová, Beata: Influence of specific properties of metal strip surfaces on their magnetic properties
(Vplyv špecifických vlastností povrchov kovových pások na ich magnetické vlastnosti)
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Supervisor: Butvinová, Beata, RNDr., CSc.
Gmucová, Katarína: Charge transport at the nanocomposite thin film / electrolyte interface
(Transport náboja na rozhraní nanokompozitných vrstiev s elektrolytom)
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Supervisor: Gmucová, Katarína, RNDr., CSc.
Annotation: The thesis will be oriented toward the analysis of charge transfer phenomena at a nanocomposite thin film / electrolyte interface. Organic semiconductor based composites with embeded nanoparticles will be studied. A comprehensive understanding of the charge transfer kinetics at thin film / electrolyte interface is a key to developing both the prospective solar cells and electrochemical sensors based on electrochemical and combined electrochemical and optical signal transduction and readout. The complex analysis of charge transfer kinetics at nanocomposite thin films will contribute to the elucidation of anomalous charge transfer origin at nanostructured interfaces and to finding the chances of its applications in photovoltaics and sensorics.
Krajčí, Marián:
(Počítačové modelovanie nanoštruktúr na povrchoch kovov)
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Supervisor: Krajčí, Marián, RNDr., DrSc.
Annotation:
Krajčí, Marián:
(Katalýza chemických reakcií na povrchoch kovov)
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Supervisor: Krajčí, Marián, RNDr., DrSc.
Mihalkovič, Marek: Search for and optimization of novel low-temperature structures
(Vyhľadávanie a optimalizácia nových nízkoteplotných atómových štruktúr)
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Supervisor: Mihalkovič, Marek, RNDr., CSc.
Annotation: Formulation of the problem is simple: given a set of chemical species, predict atomic structures they will form (at zero or finite temperature). Partial, yet critical steps in this process are search for energy-minimizing structures at given fixed chemical composition, or simpler, given the constraint of fixed numbers of atoms of each specie inside periodic cell. Even the latter, easiest problem is nowadays only solvable for up to several tens of atoms. This project will not focus on further development of the general methods, but rather adapt the current methods to selected challenging situations, when the expected optimal structrures have complex, hierarchical architecture.
The succesful applicant will use a range of methods, starting from ab-initio quantum-mechanical calculations as implemented for example in widely used package VASP, through classical molecular dynamics and/or simulated annealing schemes using empirical interactions, to methods/algorithms for efficient searches through cohesive energy landscapes like genetic algorithm. The expected outcome of this postgraduate study will be prediction of novel complex atomic structures, and understanding of their formation mechanism.
Štich, Ivan: Modeling of strain effects on structural and electronic properties of 2D systems
(Modeling of strain effects on structural and electronic properties of 2D systems)
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Supervisor: Štich, Ivan, prof. Ing., DrSc.
Goals: Development and application of computational many-body techniques, primarily fixed-node Quantum Monte Carlo (QMC) for ultra-accurate modeling of electronic and photonic properties (quasi-particle and optical band gap, excitonic binding energies, etc.) of 2D systems and specifically their response to applied strain.
Annotation: 2D materials have already revolutionized science and have the potential to radically change also the technological applications. Perhaps the technologically most important parameter of a semiconducting 2D material is the band gap, which can be tuned by a number of ways, such as number of layers, dielectric embedding, or strain. It has been shown that 2D systems are easily strainable to levels unattainable in 3D materials and that applied strain has a particularly strong effect on electronic properties of 2D systems [1]. Therefore, we will study the effect of strain on electronic properties and band gap in particular (quasiparticle gap, exciton binding energy etc.) by benchmark- quality fixed-node Monte Carlo methods [2]. We propose to study strain-induced electronic properties for a series of carefully selected systems; single-layer h-BN and MoS2. The PhD. project will be supervised at IP SAS and the PhD. student is supposed to strongly interact with the TREX: The European Center of Excellence in Exascale Computing (https://trex-coe.eu/) H2020 project at IP SAS.
References: - R. Roldán, et al., J. Phys.: Condens. Matter 27, 313201 (2015)
- T. Frank, R. Derian, K. Tokár, L. Mitas, J. Fabian, and I. Štich, Many-Body Quantum Monte Carlo Study of 2D Materials: Cohesion and Band Gap in Single-Layer Phosphorene, Phys. Rev. X 9, 011018 (2019).
Štich, Ivan: Spintronics in 2D systems
(Spintronics in 2D systems)
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Supervisor: Štich, Ivan, prof. Ing., DrSc.
Goals: Development and application of computational techniques, primarily DFT and QMC, for modeling of spin properties in 2D systems via proximity effects in van der Waals few-layers and via applied strain.
Annotation: In spintronics [1] the electron spin as the fundamental degree of freedom provides the novel functionalities for use in materials science using either spin-orbit (SO) or exchange coupling. Using computational tools, the thesis will study two means to manipulate/induce SO interaction in 2D materials, namely 1) the van der Waals proximity effect (vdW-PE) [2], and 2) the effect of applied strain [3, 4]. vdW-PE has so far been mostly studied in graphene where strong SO coupling was induced via forming a vdW multilayer with a strong SO coupling transition metal dichalcogenide, preserving the high mobility of graphene. Since SO interaction represents coupling between the spin and the orbital degrees of freedom, it is possible to indirectly affect the spin properties of the system via mechanical deformations of the system; a proposition especially useful in 2D materials which are highly strainable [3]. In the thesis we plan to proximitize and strain primarily phosphorene, which is a prominent direct gap semiconductor. The PhD. project will be supervised at IP SAS and the PhD. student is supposed to strongly interact with the SASPRO 2 project in 2D spintronics.
References: - I. Žutić, J. Fabian, and S. Das Sarma, Rev. Mod. Phys. 76, 323 (2004).
- I. Žutić, A. Matos-Abiague, B. Scharf, H. Dery, and K. Belashchenko, Mater. Today 22, 85 (2019).
- R. Roldán, A.Castellanos-Gomez, E.Cappelluti, and F. Guinea, J. Phys.: Condens. Matter 27, 313201 (2015).
- K. Zollner, P. E. Faria Junior, and J. Fabian, Phys. Rev. B 100, 195126 (2019).
Štich, Ivan: Simulation of imaging and manipulation of low-D systems with atomic force microscopy
(Simulation of imaging and manipulation of low-D systems with atomic force microscopy)
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Supervisor: Štich, Ivan, prof. Ing., DrSc.
Goals: Development and application of computational techniques, primarily DFT, for modeling of imaging and atomic and charge state manipulation of low-D systems.
Annotation: The PhD. project will focus on SPM (surface probe microscopy) techniques, AFM, STM, and KPFM (Kelvin Probe Force Microscopy), in particular. These SPM techniques typically need theoretical/simulation support for their interpretation and full understanding, which the PhD. student will provide in collaboration with our experimental partners in Japan (Osaka and Tokyo University) and China (Beijing Institute of Technology). The project will focus on low dimensional (low-D) systems, such as nanoobjects on surfaces and 2D systems. In addition, simulation of imaging [1], we will simulate AFM atomic [2] and KPFS charge state [3] manipulation. The experiments will be done at our partners in Japan and China, and the simulations, mostly density functional theory, at IP SAS. A successful PhD. student will be in direct touch with the experiments by visiting our experimental partners.
References: - Y. Naitoh, R. Turanský, J. Brndiar, Y.J. Li, I. Štich, and Y. Sugawara, Nat. Phys. 13, 663 (2017).
- Y. Adachi, J. Brndiar, H. F. Wen, Q. Zhang, M. Miyazaki, S. Thakur, Y. Sugawara, H. Sang, Y.J. Li, I. Štich, and L. Kantorovich, Comms. Mat. 2, 71 (2021).
- Y. Adachi, H.F. Wen, Q.Z. Zhang, M. Miyazaki, Y. Sugawara, H. Sang, J. Brndiar, L. Kantorovich, I. Štich, and Y.J. Li, ACS Nano 13, 6917 (2019).
Švec, Peter: Multilayered and pseudobulk metallic glasses prepared by rapid quenching of the melt
(Viacvrstvové a pseudoobjemové kovové sklá pripravené rýchlym ochladením taveniny)
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Supervisor: Švec, Peter, Ing., DrSc.
Annotation: Analysis and selection of perspective chemical composition for systems of multilayered and pseudobulk metallic glasses derived from Fe and Co-based systems with enhanced glass forming ability.
Development of methods of preparation of metallic glasses with increased thickness, preparation of metallic glasses with classical and enhanced thickness by planar flow casting. Development of alternative methods of preparation of pseudobulk metallic glasses.
Analysis of structure and properties of as-quenched systems, analysis of the evolution of structure upon transition from as-quenched metastable state, comparison with classical metallic glasses. Assessment of glass-forming ability with respect to chemical composition and preparation technology.
Švec, Peter: Bulk metallic glasses prepared by rapid quenching of the melt
(Objemové kovové sklá pripravené rýchlym ochladením taveniny)
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Supervisor: Švec, Peter, Ing., DrSc.
Annotation: Analysis and selection of perspective chemical composition for systems of bulk metallic glasses derived from Fe-based systems with enhanced glass forming ability.
Development of methods of preparation of metallic glasses with increased thickness, preparation of metallic glasses with classical and enhanced thickness by planar flow casting and by cold-mould casting. Development of alternative methods of preparation of bulk metallic glasses.
Analysis of structure and properties of as-quenched systems, analysis of the evolution of structure upon transition from as-quenched metastable state, comparison with classical metallic glasses. Assessment of glass-forming ability with respect to chemical composition and preparation technology.
Švec, Peter: Formation of nanostructures and physical properties of metastable Fe and Co-rich systems
(Vznik nanoštruktúr a fyzikálne vlastnosti metastabilných systémov bohatých na Fe a Co)
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Supervisor: Švec, Peter, Ing., DrSc.
Annotation: Preparation, structure analysis and properties of Fe and Co-rich metallic systems containing suitable glass-forming and nanocrystal-forming elements (e. g. Nb, Cu, B, P, C, etc.) prepared by rapid quenching from the melt in metastable (amorphous) state.
Analysis of thermodynamics and kinetics of structure evolution during transformation from metastable state; formation of nanocrystalline phases.
Systematic optimization of composition and thermal treatment of selected systems with the aim of attaining appropriate combinations of magnetic and mechanical properties.
Correlation of short-range ordering in as-prepared state with the local structure of phases formed during transformations and with the kinetics of their formation. Interpretation of the processes controlling phase transformations from disordered metastable state on atomic level.
Švec, Peter: Development and structure characterization of rare-earth free hard magnetic systems based on Al-Mn and Fe-Ni prepared by non-conventional solidification methods
(Vývoj a charakterizácia štruktúr magneticky tvrdých systémov bez obsahu vzácnych zemín na báze Al-Mn a Fe-Ni pripravených nekonvenčnými metódami tuhnutia taveniny)
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Supervisor: Švec, Peter, Ing., DrSc.
Goals: Replacement of rare-earth elements in permanent magnets via design of novel compositions leading to formation of hard magnetic phases. Correlation between formation of hard magnetic phases and microstructure in Al-Mn and Fe-Ni systems. Identification of atomic ordering processes and processing parameters leading to enhanced figure of merit of designed permanent magnets.
Annotation: Establishment of microstructural-magnetic correlation and identification of processing parameters governing the formation of hard magnetic phases. Development of preparation and processing routes for maximization of the figure of merit via fine composition tuning, refinement of processing and structural evolution of hard magnetic phases . Detailed microstructural and thermodynamic analysis using cutting edge methods and techniques.
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Quantum electronics, optics and optical spectroscopy (4.1.4)
Bužek, Vladimír: Engineering photon pair sources for quantum photonics applications
(Príprava dvojfotónových zdrojov pre aplikácie v kvantovej fotonike)
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Supervisor: Bužek, Vladimír, prof. RNDr., DrSc.
Goals: The main objective of this PhD project is to design and build experimental setups in order to demonstrate quantum advantage in various area like, enhanced security of communication, greater accuracy of measurement or simply studying the fundamental nature of entanglement.
Annotation: A background in photonics sciences like nonlinear optics, lasers, light propagation in complex medium and/or in material sciences like the physics of semiconductors, nanostructure, photodiodes is strongly recommended. The candidate will need to also be familiar with basic computer sciences in order to perform simulation of physical systems, control of instrumentation and custom design software for post-processing of experimental data. A candidate which is strongly motivated, independent, rigorous and organised with only some of these skills will find the perfect environment to gain the rest of them during his PhD.
Jergel, Matej: Study of Few-Layer Thin Film Growth by In-Situ X-ray Scattering
(Štúdium rastu atomárne tenkých vrstiev pomocou in-situ RTG rozptylu)
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Supervisor: Jergel, Matej, Ing., DrSc.
Goals: Research of few-layer thin-film growth in a CVD reactor utilizing X-ray scattering in real-time
Annotation: The work will be focused on the kinetics of few-layer thin-film growth, including MoS2, PtSe2 and similar. To elucidate the kinetics of thin-film growth, in-situ grazing-incidence wide-angle X-ray scattering (GIWAXS) setup adapted to a CVD chamber will be used in a laboratory. Complementary GIWAXS experiments will be conducted at synchrotrons in Grenoble (ESRF) and Hamburg (DESY). The work will be realized at the Institute of Physics, SAS. For detailed information, please write an email to: peter.siffalovic@savba.sk or call +421949556037.
References: - M. Sojkova, et al., RSC Advances 9 (2019) 29645 - 29651
Jergel, Matej: In-operando diagnostics of Li batteries using optical methods
(In-operando diagnostika Li batérií pomocou optických metód)
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Supervisor: Jergel, Matej, Ing., DrSc.
Goals: Study of charging/discharging cycles of Li-based batteries utilizing X-ray scattering and Raman spectroscopy
Annotation: We will employ in-operando X-ray scattering and Raman spectroscopy studies to follow charging/discharging processes in Li-based batteries. We will focus on Li-S batteries due to their highest available capacity. We will track the phase and particle size changes during Li-ion intercalation utilizing wide- and small-angle X-ray scattering, respectively. Furthermore, we will use Raman spectroscopy in the range between 30 – 3600 cm-1 to follow the phase changes. Complementary to X-ray scattering, we will use cyclic voltammetry to track the charging/discharging processes. The work will be realized at the Institute of Physics, SAS. For detailed information, please write an email to: peter.siffalovic@savba.sk or call +421949556037.
References: - J. Nelson, et al., J. Am. Chem. Soc. 2012, 134, 14, 6337-6343
Majková, Eva: Advanced AFM and CLSM investigations for biomedical applications
(Pokročilé AFM a CLSM metódy pre biomedické aplikácie)
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Supervisor: Majková, Eva, RNDr., DrSc.
Goals: Optimization and tracking of bioconjugated 2D materials utilizing advanced CLSM and AFM techniques
Annotation: The topic will be focused on the applications of 2D materials for advanced biomedical systems. We have recently demonstrated that suitably bioconjugated 2D materials can have increased selectivity towards cancer cells, which is generally an important step to overcome the difficulties of currently in use cancer treatments. The research will be focused on the optimization of such high selectivity towards cancers cells. The experimental work will focus on the characterization of bioconjugation of 2D materials by confocal laser scanning microscopy (CLSM) combined with advanced atomic force microscopy (AFM) in a liquid environment. The work will encompass - detailed characterization of cells via AFM and CLSM, research and design of the functionalization of AFM tips for tethering different biomolecules, AFM single-molecule force spectroscopy characterization of biomolecules towards cell membranes. The work will be realized at the Institute of Physics and Virology Institute SAS. For detailed information, please write an email to: peter.siffalovic@savba.sk or call +421949556037.
References: - Lamprecht, C. et al., Biomedical Sensing with the Atomic Force Microscope, in Bhushan B. (eds) Nanotribology and Nanomechanics. 135–173 (Springer, 2017)
- Kálosi, A. et al., A bioconjugated MoS2 based nanoplatform with increased binding efficiency to cancer cells, in Biomater. Sci. 8, 1973–1980 (2020)
Šiffalovič, Peter: Novel flexible X-ray detector based on perovskite quantum dots
(Nové ohybné RTG detektory na báze perovskitových kvantových dotov)
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Supervisor: Šiffalovič, Peter, Dr. Rer. Nat., PhD.
Goals: Study and characterization of thin films of perovskite quantum dots.
Annotation: The current X-rays detection technologies used in flat-panel detectors are mostly based on non-flexible and expensive silicon-based detectors. However, recent progress in low-dimensional perovskite materials (including perovskite quantum dots) enables the development of flexible, ultra-thin detectors with high absorption efficiency. This work will concentrate on the preparation and characterization of thin perovskite films (made of quantum dots) sandwiched between the electron and hole transporting layers. The perovskite layer effectively absorbs a photon, inducing a hole-electron pair, which will be in turn separated in the transporting layers. The work will be realized at the Institute of Physics, SAS, which poses all the necessary experimental equipment. For detailed information, please email to: peter.siffalovic@savba.sk.
References: - Y. Zhou, Y. Wang, Yan (eds.). Perovskite Quantum Dots. Springer, 2020. ISBN 978-981-15-6637-0.
Mrkývková, Naďa: Effect of defects on the efficiency of perovskite layers for optoelectronics and photovoltaics
(Vplyv defektov na účinnosť perovskitových vrstiev pre optoelektroniku a fotovoltaiku)
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Supervisor: Mrkývková, Naďa, RNDr., PhD
Goals: Study of defects in perovskite films suitable for optoelectronics employing different direct and indirect optical techniques.
Annotation: In the last decade, hybrid organic-inorganic perovskites have become the main candidates for efficient photodiodes and next-generation solar cells. Due to their high photoluminescence quantum yields (PLQY), hybrid perovskites efficiently convert injected charge carriers into light and vice versa. Although the PLQY is relatively high, further efficiency enhancement is limited by non-radiative recombination - either recombination at defects in the absorber layer or recombination of minority carriers at the perovskite-transport layer interface. The scope of this work will be to study the defects that play a crucial role in limiting the performance of photovoltaic devices and the development of efficient passivation pathways to advance efficiency further. For this purpose, optical spectroscopy methods (photoluminescence, absorbance, scanning optical microscopy) and indirect scattering methods (X-ray diffraction) will be used. The work will be carried out at the Institute of Physics of the Slovak Academy of Sciences. For detailed information, please email to: nada.mrkyvkova@savba.sk.
References: - Ye J. et. al., Angew. Chem. Int. Ed. 2021, 60, 2 – 27.
- Fu L. et. al., Energy Environ. Sci., 2020, 13, 4017 – 4056.
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Nuclear and subnuclear physics
Filip, Peter: Quantum oscillations in hadronic matter
(Kvantové oscilácie častíc v hadrónovej hmote)
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Supervisor: Filip, Peter, Mgr., PhD.
Gmuca, Štefan: Structure of compact stars
(Štruktúra kompaktných hviezd)
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Supervisor: Gmuca, Štefan, Ing., CSc.
Venhart, Martin: Nuclear isomerism in neutron-deficient Au isotopes
(Jadrová izoméria v neutrónovo-deficitných izotopoch zlata)
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Supervisor: Venhart, Martin, Mgr., PhD.
Annotation: Nuclear Isomers are long-lived excited states in nuclei. They can be used as a powerful tool for studying nuclear structure of exotic isotopes. A project of academic dissertation will deal with analyses of the data acquired with RITU and MARA separators at the University of Jyväskylä in Finland. There we performed a dedicated study of the 179Au isotope, which revealed several new isomeric states. Their half lives varies from tens on nanoseconds up to several microseconds. This allowed a new insight into nuclear structure of extremely neutron-deficient Au isotopes. Another experiment with modified focal-plane detector setup has been approved by the PAC of the University of Jyväskylä. A PhD. candidate is expected to significantly contribute to the new experiment in Jyväskylä and then to analyse and interpret data. The topic is suitable for highly motivated students with deep interest in experimental nuclear physics. Willingness to work in an international team, together with good knowledge of English language is expected.
Herzáň, Andrej: Nuclear structure study of neutron-deficient Bi-191,192 isotopes
(Štúdium štruktúry neutrónovo-deficitných izotopov Bi-191,192)
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Supervisor: Herzáň, Andrej, Mgr., PhD.
Goals: Main objective is to identify the high-spin isomeric states and their characterization. Study of low-lying collective structures, magnetic rotation and superdeformed bands will as well be performed.
Annotation: Nuclei with just one particle (proton, neutron) outside the closed shells are of a particular interest. Investigation of the neutron-deficient bismuth isotopes (Z = 83) play an important role in the understanding of shell evolution, nuclear deformation and shape coexistence phenomena in the vicinity of lead. Bi nuclei of this study are 17 and 18 neutrons, respectively, away from the doubly magic Pb-208 nucleus, relatively close to neutron mid-shell. Both the Bi-191,192 isotopes are located in the region with strong manifestation of shape coexistence and high-spin isomeric states associated with multi-quasiparticle configurations [1, 2, 3]. The Bi-191 isotope, particularly, is located right on the edge in the bismuth isotope chain, where prolate and oblate nuclear structures compete [4, 5]. The data were collected in the experiment at the Accelerator laboratory of the University of Jyväskylä (JYFL), Finland. In the data analysis, the (in-beam) gamma and decay spectroscopy tools will be used.
References: - A. Herzáň et al., Phys. Rev. C 92, 044310 (2015).
- A. Herzáň et al., Phys. Rev. C 96, 014301 (2017).
- A. Herzáň,et al., Eur. Phys. J. A 56, 165 (2020).
- P. Nieminen et al., Phys. Rev. C 69, 064326 (2004).
- M. Nyman et al., Eur. Phys. J. A 51, 31 (2015).
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Physical Engineering (5.2.48)
The topics for „Physical Engineering“ are devoted to 3 years long (4 years external) study, completed in the cooperation with FEI STU. That is why the themes are mostly identical to those for „Physics of Condensed Matter and Acoustics“ and „Quantum Electronics, Optics and Optical Spectroscopy“. We recommend viewing the topics above and also the following:
Boháč, Vlastimil: Development of the one-probe sensors and methods for the investigation of the thermal properties of materials
(Vývoj jednosondových metód na stanovenie termofyzikálnych parmetrov tuhých látok)
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Supervisor: Boháč, Vlastimil, Ing., CSc.
Annotation: The topic of the dissertation thesis is focused on the development of single-probe sensors and methods for determining the coefficients of thermal properties of materials. Specifically, it is a planar hot disk method. One of the conditions for the successful use of materials in practice for specific purposes is the estimation of the coefficients of thermal properties of materials. This allows optimizing the design of their production and their use in specific conditions. The development of sensors and methods for single-probe experimental design is required especially in the development of new technologically interesting materials and in solving problems of heat transport, either in terms of their insulating capabilities or, conversely, problems of heat dissipation in cooling equipment. The single-probe principle of the experimental setup is simpler and requires only two pieces of sample between which the sensor is placed. The planar hot disk method is therefore an interesting and necessary step to improve experimental measurement techniques. At present, several modern measuring techniques have been developed for measuring the thermal properties of materials based on the principle of transition methods. Transient dynamic or non-stationary methods use a non-stationary temperature field to characterize the thermal and heat transfer parameters of different materials. After generating a heat flow in the form of a pulse or a unit step-wise, the temperature response is sensed. By applying the appropriate physical model, the coefficients of thermal diffusivity, thermal conductivity and specific or volumetric heat capacity are sought. Temperature response sensing is performed in two ways. It is measured either at a certain distance from the pulse source or at the source location. Accordingly, we divide the sensors into two-probe and single-probe. In the case of single-probe sensors, the temperature response is sensed by the heating element itself. The output of the work will be a method that will simplify thermophysical measurements and their use in other projects.
Boháč, Vlastimil: Investigation of thermophysical properties of composites based on plastics and wood chips by dynamic methods
(Vyšetrovanie termofyzikálnych vlastností kompozitov na báze plastov a drevnej štiepky dynamickými metódami)
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Supervisor: Boháč, Vlastimil, Ing., CSc.
Annotation: The topic of this doctoral thesis is to investigate the inter-dependencies of heat transport for different compositions of wood-based composite material in conditions that simulate the conditions of real use in practice. Wood-based composites bonded with polymeric materials belong to the class of sustainable insulating materials with the potential for use in wooden buildings. Good heat-insulating properties predetermine their use in harsher climatic conditions. The effectiveness of their use in real climatic conditions depends on many parameters. Heat transfer in such materials is multi-parametric because it involves the simultaneous transfer of heat through the components of the structure. Transient thermophysical methods will be used experimentally, namely the pulse transition method and the single-probe surface hot disk method. Another task is to develop a numerical model for simultaneous heat transport by an inhomogeneous structure for wood filler having real geometry of wood filler particles. The results obtained by numerical model will be compared with the data obtained by experimental methods.
Boháč, Vlastimil: Development of sensors and measuring electronics for transient methods for determining the thermal properties of materials
(Vývoj senzorov a meracej elektroniky pre prechodové metódy na stanovenie tepelných vlastností materiálov)
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Supervisor: Boháč, Vlastimil, Ing., CSc.
Annotation: Characterization of thermo-physical properties of materials is a basic condition for their use in real or even specific conditions. At present, several modern measuring techniques have been developed based on the principle of transient methods. Transition (or dynamic) methods use a non-stationary temperature field to characterize heat transport and material parameters. After generating a heat flow in the form of a pulse or unit step, the temperature response is measured. The coefficients of thermal diffusivity and thermal conductivity as well as the specific heat capacity are sought from thermal response by applying the appropriate physical model by minimizing the parameters. Temperature response measuring is performed in two ways. Either at a certain distance from the pulse source or at the heat source or sensor location. Accordingly, we divide the sensors into two-probe and single-probe. In the case of single-probe sensors, the temperature response is sensed by the heating element itself. The development of single-probe sensors and methods for investigating the thermal properties of materials is therefore an interesting and necessary step to improve experimental measurement techniques. The development of these sensors and methods is required especially in the development of new technologically interesting materials and in solving problems of heat transport, either in terms of their insulating capabilities or, conversely, in the case of heat dissipation by radiators.
Bužek, Vladimír: Engineering photon pair sources for quantum photonics applications
(Príprava dvojfotónových zdrojov pre aplikácie v kvantovej fotonike)
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Supervisor: Bužek, Vladimír, prof. RNDr., DrSc.
Goals: The main objective of this PhD project is to design and build experimental setups in order to demonstrate quantum advantage in various area like, enhanced security of communication, greater accuracy of measurement or simply studying the fundamental nature of entanglement.
Annotation: A background in photonics sciences like nonlinear optics, lasers, light propagation in complex medium and/or in material sciences like the physics of semiconductors, nanostructure, photodiodes is strongly recommended. The candidate will need to also be familiar with basic computer sciences in order to perform simulation of physical systems, control of instrumentation and custom design software for post-processing of experimental data. A candidate which is strongly motivated, independent, rigorous and organised with only some of these skills will find the perfect environment to gain the rest of them during his PhD.
Ivančo, Ján: Trioxide tungsten films aimed at chemiresistive sensors of gaseous biomarkers of diseases
(Vrstvy trioxidu volfrámu pre chemoodporové senzory plynných biomarkerov chorôb)
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Supervisor: Ivančo, Ján, Ing., PhD.
Goals: Investigation on preparation and characterization of trioxide tungsten thin films and their sensing response towards trace concentration of acetone vapors.
Annotation: The chemiresistive sensors of gases are based on resistance change of an active layer (usually metal oxides) upon the concentration change of gaseous ambient. For the particular probed gas, the sensor can be sensitive for its concentrations down to ppb level (parts per billion). The aplicant will investigate the preparation and physico-chemical properties of trioxide tungsten (WO3) and its sensing response to trace concentrations of acetone vapors in air. The research subject aims at noninvasive monitoring of elevated sugar level in blood of diabetics as the elevated sugar level is accompanied by increased acetone concentration in the exhaled breath.
The work will be executed at Institute of Physics of Slovak Academy of Sciences. During the PhD study, the student is going to have an access to the autonomously equipped Laboratory of multilayers and nanostructures.
Mihalkovič, Marek: Search for and optimization of novel low-temperature structures
(Vyhľadávanie a optimalizácia nových nízkoteplotných atómových štruktúr)
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Supervisor: Mihalkovič, Marek, RNDr., CSc.
Annotation: Formulation of the problem is simple: given a set of chemical species, predict atomic structures they will form (at zero or finite temperature). Partial, yet critical steps in this process are search for energy-minimizing structures at given fixed chemical composition, or simpler, given the constraint of fixed numbers of atoms of each specie inside periodic cell. Even the latter, easiest problem is nowadays only solvable for up to several tens of atoms. This project will not focus on further development of the general methods, but rather adapt the current methods to selected challenging situations, when the expected optimal structrures have complex, hierarchical architecture.
The succesful applicant will use a range of methods, starting from ab-initio quantum-mechanical calculations as implemented for example in widely used package VASP, through classical molecular dynamics and/or simulated annealing schemes using empirical interactions, to methods/algorithms for efficient searches through cohesive energy landscapes like genetic algorithm. The expected outcome of this postgraduate study will be prediction of novel complex atomic structures, and understanding of their formation mechanism.
Nádaždy, Vojtech: Electrical and structural properties of perovskite and organic semiconductors for photovoltaics
(Elektrické a štruktúrne vlastnosti perovskitov a organických polovodičov pre fotovoltiku)
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Supervisor: Nádaždy, Vojtech, Ing., CSc.
Goals: Efficiency and stability increase of perovskite and organic solar cells.
Annotation: Perovskite solar cells (PSCs) are one of the hot topics in contemporary research in the 3rd generation photovoltaics. The PhD theme is focused on the preparation of perovskite and organic semiconductor layers utilized in PSCs and their systematic investigation in terms of electronic structure, crystallographic structure, morphology, interface properties and their impact on the photoconversion efficiency. Electronic structure of the layers will be investigated with a unique energy-resolved electrochemical impedance spectroscopy developed at the workplace of supervisor. Along with the analysis of other basic parameters of PSCSs such as the open-circuit voltage, short-circuit current, fill factor and power conversion efficiency, new basic knowledge on the correlation between electronic structure, electron transport properties and interface quality will be obtained.
The work will be realized at the Institute of Physics, SAS.
Nádaždy, Vojtech: Preparation and electrochemical investigation of electrodes for secondary electrochemical cells
(Príprava a elektrochemické vyšetrovanie elektród sekundárnych elektrochemických článkov)
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Supervisor: Nádaždy, Vojtech, Ing., CSc.
Goals: Development of new generation of composite electrodes for rechargeable batteries.
Annotation: Secondary electrochemical cells are rechargeable batteries that can be electrically recharged after use. This type of batteries plays an increasing role in dissemination of eco-friendly autonomous electrical facilities including vehicles. The PhD theme is focused on the development and preparation of new types of the composite cathodes and anodes for rechargeable lithium-ion and sodium-ion batteries. Using the methods of cyclic voltammetry, electrochemical impedance spectroscopy and cyclic charge-discharge, electrochemical properties of the electrodes will be studied aiming at increasing durability and improving efficiency of batteries. A unique method of the energy-resolved electrochemical impedance spectroscopy developed at the workplace of supervisor will be employed to characterize electronic structure of the electrodes. The work will be realized at the Institute of Physics, SAS.
Švec, Peter: Multilayered and pseudobulk metallic glasses prepared by rapid quenching of the melt
(Viacvrstvové a pseudoobjemové kovové sklá pripravené rýchlym ochladením taveniny)
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Supervisor: Švec, Peter, Ing., DrSc.
Annotation: Analysis and selection of perspective chemical composition for systems of multilayered and pseudobulk metallic glasses derived from Fe and Co-based systems with enhanced glass forming ability.
Development of methods of preparation of metallic glasses with increased thickness, preparation of metallic glasses with classical and enhanced thickness by planar flow casting. Development of alternative methods of preparation of pseudobulk metallic glasses.
Analysis of structure and properties of as-quenched systems, analysis of the evolution of structure upon transition from as-quenched metastable state, comparison with classical metallic glasses. Assessment of glass-forming ability with respect to chemical composition and preparation technology.
Švec, Peter: Bulk metallic glasses prepared by rapid quenching of the melt
(Objemové kovové sklá pripravené rýchlym ochladením taveniny)
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Supervisor: Švec, Peter, Ing., DrSc.
Annotation: Analysis and selection of perspective chemical composition for systems of bulk metallic glasses derived from Fe-based systems with enhanced glass forming ability.
Development of methods of preparation of metallic glasses with increased thickness, preparation of metallic glasses with classical and enhanced thickness by planar flow casting and by cold-mould casting. Development of alternative methods of preparation of bulk metallic glasses.
Analysis of structure and properties of as-quenched systems, analysis of the evolution of structure upon transition from as-quenched metastable state, comparison with classical metallic glasses. Assessment of glass-forming ability with respect to chemical composition and preparation technology.
Švec, Peter: Formation of nanostructures and physical properties of metastable Fe and Co-rich systems
(Vznik nanoštruktúr a fyzikálne vlastnosti metastabilných systémov bohatých na Fe a Co)
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Supervisor: Švec, Peter, Ing., DrSc.
Annotation: Preparation, structure analysis and properties of Fe and Co-rich metallic systems containing suitable glass-forming and nanocrystal-forming elements (e. g. Nb, Cu, B, P, C, etc.) prepared by rapid quenching from the melt in metastable (amorphous) state.
Analysis of thermodynamics and kinetics of structure evolution during transformation from metastable state; formation of nanocrystalline phases.
Systematic optimization of composition and thermal treatment of selected systems with the aim of attaining appropriate combinations of magnetic and mechanical properties.
Correlation of short-range ordering in as-prepared state with the local structure of phases formed during transformations and with the kinetics of their formation. Interpretation of the processes controlling phase transformations from disordered metastable state on atomic level.
Švec, Peter: Development and structure characterization of rare-earth free hard magnetic systems based on Al-Mn and Fe-Ni prepared by non-conventional solidification methods
(Vývoj a charakterizácia štruktúr magneticky tvrdých systémov bez obsahu vzácnych zemín na báze Al-Mn a Fe-Ni pripravených nekonvenčnými metódami tuhnutia taveniny)
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Supervisor: Švec, Peter, Ing., DrSc.
Goals: Replacement of rare-earth elements in permanent magnets via design of novel compositions leading to formation of hard magnetic phases. Correlation between formation of hard magnetic phases and microstructure in Al-Mn and Fe-Ni systems. Identification of atomic ordering processes and processing parameters leading to enhanced figure of merit of designed permanent magnets.
Annotation: Establishment of microstructural-magnetic correlation and identification of processing parameters governing the formation of hard magnetic phases. Development of preparation and processing routes for maximization of the figure of merit via fine composition tuning, refinement of processing and structural evolution of hard magnetic phases . Detailed microstructural and thermodynamic analysis using cutting edge methods and techniques.
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Šauša, Ondrej: Slow chemical reactions of photodegradation in polymers and their influence on positron formation
(Pomalé chemické reakcie fotodegradácie u polymérov a ich vplyv na tvorbu pozitrónia)
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Supervisor: Šauša, Ondrej, RNDr., CSc.
Annotation: The goal of the project is to study the formation of positronium and changes in microstructural free volume in selected types of polymers during photodegradation by UV light. At the same time, the time course of changes in chemical bonds will be monitored using infrared spectroscopy. The consequences of these processes on the material properties of the investigated polymers from the point of view of their use in practice will be evaluated. The source of positrons will be the radioisotope 22Na.
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