Disentangling orbital and spin exchange interactions for Co2+ on a rocksalt lattice

P. M. Sarte*, R. A. Cowley, E. E. Rodriguez, E. Pachoud, D. Le, V. Garcia-Sakai, J. W. Taylor, C. D. Frost, D. Prabhakaran, C. MacEwen, A. Kitada, A. J. Browne, M. Songvilay, Z. Yamani, W. J. L. Buyers, J. P. Attfield, C. Stock

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Neutron spectroscopy was applied to study the magnetic interactions of orbitally degenerate Co2+ on a host MgO rocksalt lattice where no long-range spin or orbital order exists. The paramagnetic nature of the substituted monoxide Co0.03Mg0.97O allows for the disentanglement of spin exchange and spin-orbit interactions. By considering the prevalent excitations from Co2+ spin pairs, we extract seven exchange constants out to the fourth coordination shell. An antiferromagnetic next-nearest-neighbor 180 degrees exchange interaction is dominant; however, dual ferromagnetic and antiferromagnetic interactions are observed for pairings with other pathways. These interactions can be understood in terms of a combination of orbital degeneracy in the t(2g) channel and the Goodenough-Kanamori-Anderson rules. Our work suggest that such a hierarchy of exchange interactions exists in transition-metal-based oxides with a t(2g) orbital degeneracy.

Original languageEnglish
Article number024415
Number of pages7
JournalPhysical Review B
Volume98
Issue number2
DOIs
Publication statusPublished - 17 Jul 2018

Keywords / Materials (for Non-textual outputs)

  • MAGNETIC EXCITATIONS
  • COBALT OXIDE
  • SUPEREXCHANGE INTERACTION
  • ISOLATED CLUSTERS
  • MIXED-CRYSTALS
  • SCATTERING
  • IONS
  • COO
  • ANTIFERROMAGNETISM
  • SUSCEPTIBILITY

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