Solid State III

Magnetism

The theory of magnetism is the very important part of the modern Solid State physics. It is extremely diverse: it includes subjects that are old and well established and the ones on the frontier of the current research, purely classical problems and the problems where quantum mechanics is crucial.

Education of a Solid State physicist can not be complete without a good working knowledge of the theory of magnetism.

This course will begin with the well established subjects: formation of local moments, classical theories of ordered magnetic states in metals and insulators and proceed to more modern subjects such as spin liquids and spin glasses and finally to open problems.

Preliminary plan of the course (might be revised according to the audience background and interests).

• Atomic magnetism.
• Formation of local moments in insulators: crystall field effects, chemistry approach, examples (transition metal oxides)
• Magnetism of metals: Stoner ferromagnetism, antiferromagnetism, Haubbard model, Nagaoka theorem
• Local moments in metals: Anderson impurity, Kondo problem, RKKY interaction.
• Ordered states of magnets: ferromagnets, antiferromagnets, spiral states.
• Quantum fluctuations in the ordered state of simple magnets: spin waves in ferro- and antiferromagnets.
• Quantum critical points in ferro and antiferromagnets.
• Disordered classical magnets: weak disorder, random field, Imry condition.
• Frustrated magnets: geometrical and random frustration.
• Strongly disordered classical magnets (spin glasses).
• Parisi theory of equilibrium properties, dynamical theories.
• Spin glasses without disorder.
• Quantum spin glasses.
• Spin liquids