Wei-Guo Yin, X. Liu, A. M. Tsvelik, M. P. M. Dean, M. H. Upton, Jungho Kim, D. Casa, A. Said, T. Gog, T. F. Qi, G. Cao, J. P. Hill
We report a combined experimental and theoretical study of the unusual ferromagnetism in the quasi-one-dimensional copper-iridium oxide Sr3CuIrO6. Utilizing Ir L3 edge resonant inelastic x-ray scattering, we reveal a large gap magnetic excitation spectrum, and show that it is well described by the S=1/2 Heisenberg model with an Ising-like ferromagnetic exchange anisotropy. We present a microscopic derivation of this model and find an unexpected effect, namely the ferromagnetic anisotropy arises from the antiferromagnetic superexchange interaction, driven by the alternating strong and weak spin-orbit coupling on the Ir and Cu magnetic ions, respectively. Our results point to the unusual magnetic behavior to be expected in mixed 3d-5d transition-metal compounds via exchange pathways that are absent in pure 3d or 5d compounds.
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http://arxiv.org/abs/1302.1818
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