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arXiv · 1801.10549

Lattice dynamics of ASb2O6 (A=Cu,Co) with trirutile structure

D. T. Maimone·A. B. Christian·J. J. Neumeier·E. Granado
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Abstract

Raman spectroscopy experiments on single crystals of CuSb2O6 and CoSb2O6 quasi-one-dimensional antiferromagnets with trirutile crystal structure were performed, with a focus on the first material. The observed Raman-active phonon modes and previously reported infrared-active modes were identified with the aid of ab-initio lattice dynamics calculations. The structural transition between monoclinic beta-CuSb2O6 and tetragonal alpha-CuSb2O6 phases at Ts=400 K is manifested in our spectra by a "repulsion" of two accidentally quasi-degenerate symmetric modes below Ts, caused by a phonon mixing effect that is only operative in the monoclinic beta-CuSb2O6 phase due to symmetry restrictions. Also, two specific phonons, associated with CuO6 octahedra rotation and with a Jahn-Teller elongation mode, soften and broaden appreciably as T -> Ts. A crossover from a displacive to an order-disorder transition at Ts is inferred.

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D. T. Maimone, A. B. Christian, J. J. Neumeier, E. Granado. 2018-01-31. Lattice dynamics of ASb2O6 (A=Cu,Co) with trirutile structure. https://doi.org/10.1103/physrevb.97.104304

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