Eur. Phys. J. B 61, 457-463 (2008)
https://doi.org/10.1140/epjb/e2008-00100-7

Study on the spin-states of cobalt-based double-layer perovskite Sr₂Y_0.5Ca_0.5Co₂O₇

National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, P.R. China

Corresponding author: ^a kelly_h2@hotmail.com

Received: 6 June 2007
Revised: 22 January 2008
Published online: 7 March 2008

Abstract

The spin-states of cobalt based perovskite compounds depend sensitively on the valence state and local crystal environment of Co ions and the rich physical properties arise from strong coupling among charge, spin, and orbital degrees of freedom. While extensive studies have been carried out in the past, most of them concentrated on the isotropic compound LaCoO₃. In this paper, using the unrestricted Hartree-Fock approximation and the real-space recursion method, we have investigated the competition of various magnetically ordered spin-states of anisotropic double-layered perovskite Sr₂Y_0.5Ca_0.5Co₂O₇. The energy comparison among these states shows that the nearest-neighbor high-spin-intermediate-spin ferromagnetically ordered state is the relevant magnetic ground state of the compound. The magnetic structure and sizes of magnetic moments are consistent with the recent experimental observation.