August 23rd
when: 23/08/2018, 10:30
where: KE E-541 (møterom)
speaker: Duc Le
title: Anisotropic magnetic interactions in delafossites and inelastic neutron scattering
abstract:
The delafossite crystal structure comprises layers of edge linked metal-oxygen octahedra in which the magnetic metal ions form a triangular lattice, separated by layers of linearly coordinated metal-oxygen dumb-bells which are non-magnetic. They thus form quite good realisation of a frustrated 2D triangular lattice and many compounds in the series adopt non-collinear magnetic structures and/or are multiferroic. This talk will focus on the chromium delafossites, which have a common magnetic structrure where neighbouring spins are rotated by 120 degrees w.r.t. each other, but the spins lie in a vertical plane thus breaking the inversion symmetry at the Cr site. We have used inelastic neutron scattering to determine the exchange interactions and single-ion anisotropy in PdCrO2 and conclude that this magnetic structure is stabilised by a combination of an anisotropic dipolar interaction and the frustrated triangular geometry of the compounds.