Magnetic state of pyrochlore Cd2Os2O7 emerging from strong competition of ligand distortions and longer-range crystalline anisotropy
journal contributionposted on 14.08.2018, 15:52 by Nikolay A. Bogdanov, Remi Maurice, Ioannis RousochatzakisIoannis Rousochatzakis, Jeroen van den Brink, Liviu Hozoi
By many-body quantum-chemical calculations, we investigate the role of two structural effects - local ligand distortions and the anisotropic Cd-ion coordination - on the magnetic state of Cd2Os2O7, a spin S=3/2 pyrochlore. We find that these effects strongly compete, rendering the magnetic interactions and ordering crucially dependent on these geometrical features. Without trigonal distortions, a large easy-plane magnetic anisotropy develops. Their presence, however, reverses the sign of the zero-field splitting and causes a large easy-axis anisotropy (D-6.8 meV), which in conjunction with the antiferromagnetic exchange interaction (Ja6.4 meV) stabilizes an all-in-all-out magnetic order. The competition uncovered here is a generic feature of pyrochlore magnets.
N. A. B. and L. H. acknowledge financial support from the Erasmus Mundus Programme of the European Union and the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG), respectively.