Condensed Matter Physics Seminar
Note Special Time:
2 p.m., Friday, March 10, 2006
Room 1201, Physics Building
Magnetization Plateaux in Cr
Spinels
(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.
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Host: Prange
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