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Study program: Physics of condensed matter

Theme: The influence of exchange anisotropy and single-ion anisotropy on magneto-thermal properties of selected low-dimensional magnets.

Supervisor: RNDr. Erik Čižmár, PhD.

Form of study: daily

Annotation: Thesis is devoted to the experimental study of selected low-dimensional magnets with aim to study the influence of exchange anisotropy and single-ion anisotropy on field-induced change of their excitation spectra which may lead to increased change of magnetic entropy and enhanced magnetocaloric effect. The aim the study will be evaluation of entropy change and effectivity of magnetic cooling during adiabatic magnetization or demagnetization at low temperatures. Analysis of EPR spectra, magnetic and thermodynamic properties at low-temperatures will be performed for determination of characteristic parameters of magnetic system and their relation to possible magnetic cooling. Studied low-dimensional magnets will be based on transition metal ions Cu, Ni and also high-spin systems based on Mn ions.

Theme: Magnetization processes of soft magnetic composites

Supervisor: Prof. RNDr. Peter Kollár, DrSc.

Form of study: daily

Annotation: The study is oriented on investigation of the magnetization reversal processes in soft magnetic composites as a function of magnetic field after demagnetization or at magnetization reversal on minor hysteresis loops in DC and AC magnetic fields. The aim is to investigate reversible and irreversible magnetization processes and their influence on macroscopic magnetic parameters of the composite material.


Theme: Magnetocaloric effect and relaxation phenomena in quantum and nanoscopic systems.

Supervisor: Prof. Ing. M. Orendáč, CSc.

Consultant: Assoc. Prof. RNDr. A. Zeleňáková, PhD.

Form of study: daily

Annotation: The thesis is focused on the investigation of magnetocaloric effect and spin dynamics in the selected types of quantum magnetic systems. The studied systems will be prepared by methods of chemical synthesis and litographic technique. Experimental study will involve measurements of specific heat, susceptibility, magnetization at low temperatures and high magnetic fields. If a need arises, electron – spin resonance and infrared spectra will be added to the package of the data. The obtained data will be analyzed using current theoretical models to understand static and dynamic properties of low – energy states of the studied systems. This thesis offers the PhD. student skills in operating commercial devices for measurements of thermodynamic quantities at low temperatures, litographic technology for the preparation of samples. He will be involved in extending magnetocaloric measurements to milikelvin temperature range in a 3He – 4He dilution refrigerator. In addition, he will acquire physical insight in the relevant part of quantum magnetism, which together with experimental skills, will be completed by his abilities to work with commercial software packages for developing programs for measurements and data acquisition.

Theme: Influence of spin and spatial anisotropy on the magnetic properties of low-dimensional quantum magnets in the wide range of magnetic fields.

Supervisor: Assoc. Prof. RNDr. Alžbeta Orendáčová, DrSc.

Consultant: RNDr. Robert Tarasenko, PhD.

Form of study: daily

Annotation: In the nature, there can occur neither systems with perfect isotropy of spatial distribution of exchange interactions, nor those with the equal importance of all individual spin components acting in the exchange coupling. Importance of individual spin components is governed by spin-orbit coupling, projecting lattice symmetry to the spin system. As a result, in the nature, there is no spin isotropic (Heisenberg) system in the critical region. It occurs in the vicinity of a phase transition and in low-dimensional systems at all temperatures below the phase transition. The work is focused on the study of selected low-dimensional quantum magnets with various kind of lattice symmetry. Special attention will be given to the systems with the spin easy-plane (XY) anisotropy, which induces topological excitations vortices (V) and antivortices (AV). These excitations play a key role in the topologic phase transition, below which, the topological excitations can exist only in the form of bound V+AV pairs. The stability of the topological formations will be studied with respect to deviations from the XY anisotropy, mainly in the case of XYhp symmetries, i.e., when a few, p preferred directions occurs in the easy plane. It happens in all real systems as a result of magnetic field effect (p = 1), or the lattice symmetry (p = 2, 4, 6). For this purpose, various experimental techniques will be applied, including electron paramagnetic resonance, magnetization, susceptibility, specific heat and thermal conductivity. When need arises, further techniques will be used which are not implemented in the laboratories of P.J. Šafárik University.

Theme: In-situ depth profiling and scanning tunneling microscopy/spectroscopy of superconductors

Supervisor: Mgr. Tomas Samuely, PhD.

Consultant: Mgr. Pavol Szabó, CSc.

Form of study: daily

Annotation: Scanning tunneling spectroscopy is the perfect tool for the investigation of superconducting materials, since it is extremely sensitive to the slightest differences in the local density of states. As such, however, its ability to provide relevant information about the local physical properties is often obstructed by the degradation of the sample surface exposed to air. Our newly installed ultra-high vacuum system features an Ar ion sputtering gun for in-situ etching of the sample surface. The sample can be transferred subsequently into the integrated low-temperature scanning tunneling microscope without the necessity of being exposed to air. In addition, the etching process can be directly monitored by the X-ray photoelectron spectroscopy, providing the information about the chemical composition of the surface. This method is also integrated within the ultra-high vacuum system. Furthermore, by repetitive etching of the sample, depth profiling of inhomogeneous samples can be performed. The main goal of the thesis will be to devise and fine-tune a protocol for in-situ surface cleaning, depth profiling and tunneling spectroscopy and the investigation of unconventional superconductors by all three methods combined.

Ultra-high vacuum system by Specs, incorporating Ar ion sputtering, X-ray photoelectron spectroscopy, low-temperature scanning tunneling microscope with a 3 T magnet and other techniques.

Theme: Manipulation with domain wall in thin magnetic wires.

Supervisor: Assoc. Prof. RNDr. Rastislav Varga, DrSc.

Consultant: RNDr. Kornel Richter, PhD.

Form of study: daily

Annotation: The aim of the work is to study the possibility of manipulation of the domain wall propagation in thin magnetic wires by controlling its shape, structure, induced anisotropy, etc.

Theme: The study of dynamic magnetic properties and relaxation process in magnetic nanoparticles.

Supervisor: Assoc. Prof. RNDr. Adriana Zeleňáková, PhD.

Form of study: daily

Annotation: Mono-domain metal nanoparticles based on iron and cobalt are of great interest due to their intrinsic physical properties, such as macroscopic quantum tunnelling (MQT), quantum size effects, giant magnetic moment and surface spin frustration interplaying between the surface and core atoms. The spin structure of nanoparticles can be affected by inter-particle interactions. One of the powerful ways how to get a better insight into the nature of inter-particle interactions and estimate their strong is the analysis of ac magnetic susceptibility. The PhD. study is oriented on investigation of dynamic magnetic properties and analyses of relaxation processes. The aim is to study the possibility of change in relaxation processes by controlling the inter-particle interactions, energy barrier distribution, particles size, etc.



Otvorenie Relaxačného kútika Mark pre študentov


Selected topics in magnetism




Pavol Jozef Šafárik University in Košice
Faculty of Science UPJŠ


Department of Biophysics
Department of Condensed Matter Physics
Department of Nuclear Physics and Subnuclear Physics
Department of Theoretical Physics and Astrophysics
Division of Didactics of Physics


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