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arXiv · 1102.0469

Elastic Instabilities within Antiferromagnetically Ordered Phase in the Orbitally-Frustrated Spinel GeCo$_2$O$_4$

Tadataka Watanabe·Shigeo Hara·Shin-Ichi Ikeda·Keisuke Tomiyasu
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Abstract

Ultrasound velocity measurements of the orbitally-frustrated GeCo$_2$O$_4$ reveal unusual elastic instabilities due to the phonon-spin coupling within the antiferromagnetic phase. Shear moduli exhibit anomalies arising from the coupling to short-range ferromagnetic excitations. Diplike anomalies in the magnetic-field dependence of elastic moduli reveal magnetic-field-induced orbital order-order transitions. These results strongly suggest the presence of geometrical orbital frustration which causes novel orbital phenomena within the antiferromagnetic phase.

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Tadataka Watanabe, Shigeo Hara, Shin-Ichi Ikeda, Keisuke Tomiyasu. 2011-06-16. Elastic Instabilities within Antiferromagnetically Ordered Phase in the Orbitally-Frustrated Spinel GeCo$_2$O$_4$. https://doi.org/10.1103/physrevb.84.020409

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