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Spin excitations in the antiferromagnet NaNiO2

Sophie De Brion·C. Darie·M. Hopzapfel·D. Talbayev·L. Mihaly·F. Simon·A. Janossy·G. Chouteau
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Abstract

In NaNiO2, Ni3+ ions form a quasi two dimensional triangular lattice of S = 1=2 spins. The magnetic order observed below 20K has been described as an A type antiferromagnet with ferro- magnetic layers weakly coupled antiferromagnetically. We studied the magnetic excitations with the electron spin resonance for frequencies 1-20 cm-1, in magnetic fields up to 14 T. The bulk of the results are interpreted in terms of a phenomenological model involving bi-axial anisotropy for the spins: a strong easy-plane term, and a weaker anisotropy within the plane. The direction of the easy plane is constrained by the collective Jahn-Teller distortion occurring in this material at 480 K.

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Sophie De Brion, C. Darie, M. Hopzapfel, D. Talbayev, L. Mihaly, F. Simon, A. Janossy, G. Chouteau. 2006-08-10. Spin excitations in the antiferromagnet NaNiO2. https://doi.org/10.1103/physrevb.75.094402

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