Kirill Povarov: Katalogdaten im Frühjahrssemester 2021

NameHerr Dr. Kirill Povarov
Otto-Stern-Weg 1 / HPF F 22
Lab. für Festkörperphysik
8093 Zürich
Telefon+41 446334927

402-0532-50LQuantum Solid State Magnetism II6 KP2V + 1UK. Povarov
KurzbeschreibungThis course covers the modern developments and problems in the field of solid state magnetism. It has the special emphasis on the phenomena that go beyond semiclassical approximation, such as quantum paramagnets, spin liquids and magnetic frustration. The course is aimed at both the experimentalists and theorists, and the theoretical concepts are balanced by the experimental data.
LernzielLearn the modern approach to the complex magnetic phases of matter and the transitions between them. A number of theoretical approaches that go beyond the linear spin wave theory will be discussed during the course, and an overview of the experimental status quo will be given.
Inhalt- Phase transitions in the magnetic matter. Classical and quantum criticality. Consequences of broken symmetries for the spectral properties. Absence of order in the low-dimensional systems. Berezinskii-Kosterlitz-Thouless transition and its relevance to “layered” magnets.

- Failures of linear spin wave theory. Spin wave decays. Antiferromagnets as bosonic systems. Gapped “quantum paramagnets” and their phase diagrams. Extended spin wave theory. Magnetic “Bose-Einstein condensation”.

- Spin systems in one dimension: XY, Ising and Heisenberg model. Lieb-Schultz-Mattis theorem. Tomonaga-Luttinger liquid description of the XXZ spin chains. Spin ladders and Haldane chains. Critical points in one dimension and generalized phase diagram.

- Effects of disorder in magnets. Harris criterion. “Spin islands” in depleted gapped magnets.

- Introduction into magnetic frustration. Order-from-disorder phenomena and triangular lattice in the magnetic field. Frustrated chain and frustrated square lattice models. Exotic magnetic states in two dimensions.
SkriptA comprehensive textbook-like script is provided.
LiteraturIn principle, the script is sufficient as study material. Additional reading:

-"Interacting Electrons and Quantum Magnetism" by A. Auerbach
-"Basic Aspects of The Quantum Theory of Solids " by D. Khomskii
-"Quantum Physics in One Dimension" by T. Giamarchi
-"Quantum Theory of Magnetism: Magnetic properties of Materials" by R. M. White
-"Frustrated Spin Systems" ed. H. T. Diep
Voraussetzungen / BesonderesPrerequisite:
402-0861-00L Statistical Physics
402-0501-00L Solid State Physics

Not prerequisite, but a good companion course:
402-0871-00L Solid State Theory
402-0257-00L Advanced Solid State Physics
402-0535-00L Introduction to Magnetism
402-0532-00L Quantum Solid State Magnetism I