E-book

Michal Jaščur

This is a supporting text for the undergraduate students interested in quan- tum theory of magnetism. The text represents an introduction to various theoretical approaches used in this eld. It is an open material, in the sense that it will be supported by appropriate problems to be solved by student at seminars and also as a homework.

The text consists of four chapters that form closed themes of the in- troductory quantum theory of magnetism. In the rst part we explain the quantum origin of the magnetism illustrating the appearance of the ex- change interaction for the case of hydrogen molecule. The second chapter is devoted to the application of the Bogolyubov inequality to the Heisenberg model and it represents the part which is usually missing in the textbooks of magnetism. The third chapter deals with the standard spin wave-theory including the Bloch and Holstein-Primakoff a approach. Finally, we discuss the application of the Jordan-Wigner transformation to one-dimensional spin-1/2 XY model.

The primary ambition of this supportive text is to explain diverse math- ematical methods and their applications in the quantum theory of mag- netism. The text is written in the form which should be sufficient to de- velop the skills of the students up to the very high level. In fact, it is expected that students following this course will able to make their own original applications of the methods presented in this book.

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E-book

Michal Jaščur - Michal Hnatič

This textbook covers the fundamentals of phenomenological thermodynamics to the extent typically taught in standard theoretical physics courses at the undergraduate level in the Physics degree program. A slightly reduced scope is also taught in all interdisciplinary study programs combined with physics. In recent years, the time allocation for individual courses has been slightly reduced, which is reflected in our selection and coverage of topics.

Our primary aim was to provide a sufficiently solid explanation of the key concepts and laws of thermodynamics necessary for mastering further theoretical physics courses at the master's level (e.g., Statistical Physics, Condensed Matter Physics, Quantum Theory of Solids, Quantum Theory of Magnetism, etc.). The book also presents the essential minimum knowledge required for the study of further applications of thermodynamics in biophysics, biology, chemistry, and engineering disciplines.

Understanding individual sections, as well as the text as a whole, requires a grasp of the basic concepts of thermodynamics at the level of a General Physics course and knowledge equivalent to a standard university mathematics course. Each topic is treated with the utmost emphasis on conceptual clarity and mathematical rigor.

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E-book

Michal Jaščur

This monograph is devoted to the discussion of effective field theory based on the differential operator method, originally introduced by Honmura and Kaneyoshi in 1979, which remains actively used for theoretical studies of localized spin models of magnetism—particularly variants of the Ising model. To date, this methodology has been applied by numerous authors to investigate a wide range of systems, including crystalline systems, diluted magnetic systems, systems with random exchange interactions, amorphous magnetic materials, systems under random magnetic and crystalline fields, thin magnetic layers, magnetic systems with free surfaces, binary and ternary magnetic alloys, among others.

During my scientific career, I have collaborated with several leading experts in this field—including Prof. Kaneyoshi, with whom I completed two long-term research stays—to advance the development of the differential operator method (and consequently effective field theory). Within this research area, I have published over 40 scientific papers in prominent international physics journals. These works include both methodological advancements and significant applications that predict intriguing physical phenomena, such as multicompensation phenomena in ferrimagnets.

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Michal Jaščur -Michal Hnatič

In the textbook, the processes belonging to an area of  nonequilibrium physics, which make the basis for the study and analysis of compex phenomena  of statistical mechanics, are described. The Boltzmann equation for distribution function is derived and on this basis the hydrodynamic equations are constructed.  Stochastic processes are described separately and Fokker-Planck equation for density probability  is derived. Textbook is intended for the students of second year of master study at Faculty of Science of P. J. Šafarik University.   

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