Geometrically frustrated magnets

Note: 1:45 PM
Speaker: Arnab Sen, Boston University

When: September 30, 2009 (Wed), 01:45PM to 02:45PM (add to my calendar)

This event is part of the Condensed Matter Theory Seminar Series.

Abstract: Well-formed magnetic moments (`spins’) in insulators often display dominant short-range exchange interactions, which result in sharply defined transitions from high-temperature paramagnetic behaviour to low temperature magnetic order the nature of which can usually be understood in terms of the unique minimum of the classical exchange energy. However, in some cases, the leading exchange interactions compete with each other due to the geometry of the lattice. Such geometrically frustrated systems often have many local minima in their classical energy landscape, or even a macroscopic number of inequivalent classical ground states, which leads to very different physics from unfrustrated magnets.

In this talk, I will start by explaining some general features about geometrically frustrated magnets, and then go on to describe our recent work on $S>3/2$ spin systems with easy-axis anisotropy on the kagome and triangular lattices (two well known lattices where many experimental realizations of frustrated magnets exist) where quantum fluctuations lead to interesting low temperature physics.