Frustrated magnets: anisotropy and and inhomogeneities

Abstract

The concepts of order, disorder, and spontaneous symmetry breaking - as initially formalized in Landau's seminal work on Phase Transitions - constitute the bases of our modern understanding of several exciting phenomena in Condensed Matter Physics. Recently, however, our view of these basic concepts was substantially expanded, primarily because of the frustrated magnets. Every day, novel phases, both solid (with magnetic order) and liquid (without magnetic order) are proposed and observed in these systems in the low-temperature regime. The primary goal of this project is to discover and study unusual phases of the matter occurring in strongly correlated systems in the presence of frustration, inhomogeneities, and external perturbations such as magnetic fields. We seek to identify not only new ground states, but also to investigate the low energy excitation spectrum, which we employ to study the thermodynamical, spectroscopic, and transport responses of the phases. To implement this program, we will combine analytical techniques (such as slave particle mean-field theories and spin-waves) and numerical techniques (such as classical and variational Monte Carlo and exact diagonalization). Key ingredients in our investigation are strong electron-electron interaction, appreciable spin-orbit coupling, geometrically frustrated lattices, and deviation from the crystalline structure. (AU)