Theoretical Physics Colloquium

Geometrically frustrated magnetism

by Prof. Kedar Damle (TIFR)

Sunday, April 5, 2009 from to (Asia/Kolkata)
at Colaba Campus ( AG-69 )
When electron-electron interactions overwhelm the kinetic energy of electrons in solids to localize them, one obtains `Mott insulators', in which the localized electrons give rise to magnetic moments on a regular array of lattice sites. These magnetic moments or spins are usually subject to an antiferromagnetic `exchange' coupling with each of their neighbours, which, in the simplest of cases, gives rise to long range antiferromagnetic order below a transition temperature set by the exchange energy scale.

However, if the geometry of the lattice causes the various antiferromagnetic exchange interactions to compete with each other, the antiferromagnetic order is dramatically suppressed. This can give rise to a large window in temperature with unusual `spin-liquid' behaviour, which, in certain special cases, can even persist to zero temperature and give rise to a quantum spin liquid ground state. I will discuss some of this in more detail, and then talk about some of our recent work on impurity effects in such magnets.
Organised by Dr. Vikram Tripathi