Condensed Matter Physics Seminar

Note Special Time:
2 p.m., Friday, March 10, 2006

Room 1201, Physics Building

 Magnetization Plateaux in Cr Spinels

Nic Shannon

(University of Bristol)

Abstract:  CdCr2O4 is a insulating spinel oxide whose magnetic ions occupy the sites of a three-dimensional pyrochlore lattice. The pyrochlore lattice is built of corner sharing tetrahedra, and is so frustrated that nearest neighbour antiferromagnetic interactions alone cannot select a unique ground state. Lattice distortion, however, provides an extremely efficient way of lifting this ground state degeneracy. When a magnetic field is applied to CdCr2O4, it undergoes a series of magnetic and structural phase transitions determined by the subtle interplay between elastic and magnetic energies. I present a simple theory of the magnetization process of CdCr2O4 which captures the essential features of these different phases and, in particular, offers an explanation of the striking plateau observed at half-magnetization.
Host:  Prange
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