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arXiv · 1508.01653

Observation of the orbital quantum dynamics in the spin-1/2 hexagonal antiferromagnet Ba3CuSb2O9

Yibo Han·Masayuki Hagiwara·Takehito Nakano·Yasuo Nozue·Kenta Kimura·Mario Halim·Satoru Nakatsuji
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Abstract

We explore orbital dynamics in the spin liquid candidate Ba3CuSb2O9 using multi-frequency electron spin resonance. We prepared two high quality single crystals. The crystal with a slight copper deficiency shows a structural phase transition at around 200 K due to the cooperative Jahn-Teller effect, accompanied with orbital ordering. In contrast, the crystal with almost perfect stoichiometry shows no orbital ordering down to the lowest temperature of 1.5 K. Dramatic change in the g-factor anisotropy as a function of frequency and temperature demonstrates orbital quantum fluctuations at a nearly constant time scale of ~ 100 ps below 20 K, evidencing the emergence of an orbital liquid state in this quantum spin liquid compound.

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Yibo Han, Masayuki Hagiwara, Takehito Nakano, Yasuo Nozue, Kenta Kimura, Mario Halim, Satoru Nakatsuji. 2015-08-07. Observation of the orbital quantum dynamics in the spin-1/2 hexagonal antiferromagnet Ba3CuSb2O9. https://doi.org/10.1103/physrevb.92.180410

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