Valence, spin, and orbital state of Co ions in one-dimensional Ca3 Co2 O6: An x-ray absorption and magnetic circular dichroism study

T. Burnus (1) , Z. Hu (1) , M.W. Haverkort (1) , J.C. Cezar (2) , Delphine Flahaut (3) , V. Hardy (4) , A. Maignan (4) , N.B. Brookes (2) , A. Tanaka (5) , H.H. Hsieh , H.-J. Lin , C.T. Chen , L.H. Tjeng (1)

1 Universität zu Köln = University of Cologne
2 ESRF - European Synchrotron Radiation Facility [Grenoble]
3 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux
4 CRISMAT - Laboratoire de cristallographie et sciences des matériaux
5 Hiroshima University

We have investigated the valence, spin, and orbital state of the Co ions in the one-dimensional cobaltate Ca3 Co2 O6 using x-ray absorption and x-ray magnetic circular dichroism at the Co- L2,3 edges. The Co ions at both the octahedral Cooct and trigonal Cotrig sites are found to be in a 3+ state. From the analysis of the dichroism we established a low-spin state for the Cooct and a high-spin state with an anomalously large orbital moment of 1.7 μB at the Cotrig 3+ ions. This large orbital moment along the c -axis chain and the unusually large magnetocrystalline anisotropy can be traced back to the double occupancy of the d2 orbital in trigonal crystal field. © 2006 The American Physical Society.

Domaines: Matériaux; Chimie théorique et/ou physique

T. Burnus, Z. Hu, M.W. Haverkort, J.C. Cezar, Delphine Flahaut, et al.. Valence, spin, and orbital state of Co ions in one-dimensional Ca3 Co2 O6: An x-ray absorption and magnetic circular dichroism study. Physical Review B, 2006, 74 (24), pp.245111. ⟨10.1103/PhysRevB.74.245111⟩. ⟨hal-01499379⟩