PHY667: Quantum magnetism

        [Cr:4, Lc:3, Tt:1, Lb:0]

Course Outline

• Introduction: Basic magnetic properties, units in magnetism, magnetic moments and angular momentum, Bohr magneton, precession, quantum mechanics of the spin.

• Isolated Magnetic moments: Magnetization and magnetic susceptibility, paramagnetism and dia-magnetism, Brillouin function, Van-Vleck Paramagnetism, Hund’s rules for the ground state of ions, adiabatic de-magnetization.

• Magnetic moments in solids: Crystalline electric fields, splitting of orbital degeneracy, orbital angular momentum quenching, Jahn-Teller distortion.

• Interactions between Magnetic moments: Dipolar interactions, exchange interactions, origin of exchange, super-exchange and double exchange interactions, RKKY interaction.

• Magnetic ordering: Ferro-, Ferri-, and anti-ferromagnetic ordering, Weiss molecular field models of magnetic ordering, spin glasses, excitations of the ordered states, magnons, spin-waves.

• Measuring Magnetism:
  1. Bulk techniques - Magnetometers, vibrating sample magnetometer (VSM), SQUID based magnetometers.

  2. Microscopic techniques - neutron scattering, Nuclear Magnetic Resonance (NMR), Electron Spin Resonance (ESR), and muon spin rotation (muSR).

• Special Topics: Hubbard model, Mott insulators, Magnetism in low-dimensional and geometrically frustrated systems, BEC of Magnons, quantum spin liquids.

Recommended Reading

• J. Crangle and E. Arnold, Solid State Magnetism,(1991).
• S. Blundell, Magnetism in Condensed Matter, (Oxford University Press 2005).
• P. Mohn, Magnetism in the Solid State, (Springer, 2005).
• Ashcroft and Mermin, Solid State Physics.