Study program: Condensed Matter Physics
Theme: Investigation of properties of superconductor-semiconductor
heterostructures.
Supervisor: Prof. RNDr. Alexander Feher, DrSc.
Consulant: Mgr. Vladimír Komanický, PhD.
Annotation: Superconductor-semiconductor devices have become a topic of
intensive research in recent years. They provide excellent systems to study transport
phenomena in superconductor -normal conductor
structures. Due to the
superconducting energy gap, nonlinear effects in the conductance are already present
at very low voltages. One of the most interesting phenomena that may occur at the
interface between a superconductor and a normal metal is Andreev reflection. Also
when the light is shined on the semiconductor with the wavelength corresponding to
band gap, carriers in the semiconductor can be excited which can potentially lead to
rising of interesting new phenomena in these structures. The topic of this PhD
dissertation is preparation of superconductor-semiconductor heterostructures and
study of their physical properties. The literature overview will be done first. Then
various types of the superconductor-semiconductor heterostructures will be prepared
by magnetron sputtering and their electrical transport properties and optical properties
will be studied at low temperatures.
Literature:
1. Konrad W. Lehnert, Nonequilibrium dynamics in mesoscopic superconductorsemiconductor-superconductor junctions, Dissertation, UC Santa Barbara, 1999.
Theme: Nanostructured materials for applied catalysis.
Supervisor: Prof. RNDr. Alexander Feher, DrSc.
Consulant: Mgr. Vladimír Komanický, PhD.
Annotation: Sustainability of energy resources is one of the major hurdles each developed
country is facing today. To render production of fuels sustainable, one must either close the
carbon cycle that is to use CO2 and water to make "synfuels" through different catalytic
processes or to use some alternative cycle. One of the alternatives to the carbon cycle, which
is technologically most developed is a hydrogen (water) cycle through photovoltaics,
electrolysis (photoelectrocatalysis) and fuel cells. Fuel cells and electrolyzers are energy
conversion systems that are currently available for use in the hydrogen cycle. However, they
are all plagued by one major problem, i.e. the involvement of precious metal catalysts, which
are very expensive and thus represent a large portion of the total price of these systems In
order to reduce the amount of precious metal in the relevant energy conversion devices, one
has to improve the activity, stability and selectivity of precious metal based catalysts. The
topic of this PhD dissertation is preparation of nanostructured catalytic materials
using sputtering and nanofabrication methods to prepare novel nanomaterials with
higher activity, stability and selectivity. The literature overview will be done first.
Prepared catalytic materials will be studied by atomic force microscopy, electron
microscopy and their catalytic activity will be determined.
Literature:
1. Heiz, Ulrich; Landman, Uzi (Eds.), Nanocatalysis, Springer, 2007.
Theme: Experimental study of selected low-dimensional magnets with an energy
gap in
the excitation spectrum
Supervisor: RNDr. Erik Čižmár, PhD.
Annotation: Thesis will be devoted to the study of low-dimensional magnets with an
energy gap in the excitation spectrum with aim to observe novel quantum phase
transitions. Experimental work will include the automation a tuning of the
measurement techniques for specific heat and electron spin resonance at low
temperature. The theoretical knowledge of the low-dimensional magnets theory and
quantum phase transition will be acquired by the student. Student will perform
magneto-structural analysis, ESR, magnetic and thermodynamic measurements of
selected low-dimensional magnets. The results will be published at international
conferences and published in CC journals.
Literature:
1. Schollwöck, U.; Richter, J.; Farnell, D.J.J.; Bishop, R.F. (Editors), Quantum
Magnetism,
Springer, World Scientific, London, 2004.
2. Parkinson, J.B., Farnell, D.J.J., An Introduction to Quantum Spin Systems,
Springer, 2010.
Theme: Heusler alloys prepared by rapid quenching method
Supervisor: doc. RNDr. Rastislav Varga, PhD.
Consultant: doc. RNDr. Zuzana Vargová, PhD.
Annotation: The aim of the thesis is to study the preparation of Heusler alloys by
rapid quenching method in the shape of bulk or ribbon. Consequently, magnetic,
structural and electrical characterization of such alloys will be performed.
Literature:
1. T. Krenke, E. Duman, M. Acet, E. F. Wassermann, X. Moya, L. Mañosa, A.
Planes, Nat. Mater. 4 (2005) 450.
2. B. Hernando, J.L. Sánchez Llamazares, J.D. Santos, Ll. Escoda, J.J. Suñol, R.
Varga, D. Baldomir, D. Serantes, Appl. Phys. Lett. 92 (2008) 042504.
Theme: The influence of thermal treatment on structural and magnetic
properties of rapidly quenched soft magnetic materials.
Supervisor: doc. RNDr. Rastislav Varga, PhD.
Consultant: prof. RNDr. Pavol Vojtanik, DrSc.
Annotation: The aim of the thesis is to study the influence of thermally induced
anisotropy (under mechanical stress, magnetic field, etc…) on magnetic properties of
rapidly quenched soft magnetic materials in the shape of ribbon and glass-coated
microwires.
Literature:
1. K. Richter, R. Varga, G. A. Badini-Confalonieri and M. Vázquez, Appl. Phys. Lett.
96 (2010) 182507.
2. J. Olivera, R. Varga, V. M. Prida, M. L. Sanchez, B. Hernando, and A. Zhukov
Phys. Rev.
B 82 (2010) 094414.
Theme: Study of structure and physical properties of amorphous and
nanocrystalline
alloys.
Supervisor: Prof. RNDr. Pavol Sovák, CSc.
Annotation: Main purpose of the project is to handle technology of production
amorphous and nanocrystalline alloys by rapid quenching. Due to chemical
composition or annealing treatment to optimize physical properties of produced
alloys. For structural characterization to use mainly electron microscopy techniques.
Literature:
1. P. Sovák, A Zorkovská, Structure and magnetic properties of Finemet basd alloys,
P.J.
Šafárik University in Košice, 2008, ISBN:978-80-7097-719-4.
2. Carl C. Koch, Nanostructured materials, WA Publishing, 2007, ISBN: 0-81551534-0.
3. M.A White, Physical properties of materials, CRC Press 2012, ISBN: 978-1-43986651-1.
Theme: Magnetism and magnetostructural correlations in genuine organic and
organometalic TCNQ-based materials.
Supervisor: RNDr. Marcela Kajňaková, PhD.
Consulant: RNDr. Erik Čižmár, PhD.
Anotation: The Ph.D work is aimed at the magnetism and magnetostructural
correlations of new genuine organic and organo-metalic materials based on the anionradical TCNQ (7, 7, 8, 8 – tetrakyanochinodimethane), i.e. materials with a chargetransfer. The literature information overview about this theme is assumed at the first.
The experimental study of the thermodynamic, magnetic and transport properties will
be done. The experimental data will be analyzed by theoretical models and by the
study of crystal structure. The main goal of the work is to define magnetic properties
and the magnetic system of studied material.
Literature:
K. Ariga, T. Kunitake: Supramolecular chemistry - Fundamentals and Applications.
Springer, Berlin 2006.
J. Fraxedas: Molecular Organics Materials: From Molecules to Crystalline Solids.
Cambridge University Press 2006.