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arXiv · 2110.15068

Observation of topological $Z_2$ vortex fluctuations in the frustrated Heisenberg magnet NaCrO$_2$

K. Tomiyasu·Y. P. Mizuta·M. Matsuura·K. Aoyama·H. Kawamura
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Abstract

Spin fluctuations in the triangular-lattice Heisenberg antiferromagnet NaCrO$_2$ are investigated by means of quasi-elastic neutron scattering with high energy resolution and wide energy band. Two components with the following features are captured separately. They are pronounced at intermediate temperatures of 20-50 K. One with quite an extended lifetime corresponding to $\sim$$0.001E_{\rm ex}$ ($E_{\rm ex}$ the exchange energy) nearly disappears at low temperature 10 K, and the other with an extended lifetime $\sim$$0.01E_{\rm ex}$ survives there, identified as free $Z_2$ vortex and $Z_2$-vortex pair, respectively, in harmony with the $Z_2$ vortex theory.

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K. Tomiyasu, Y. P. Mizuta, M. Matsuura, K. Aoyama, H. Kawamura. 2022-07-12. Observation of topological $Z_2$ vortex fluctuations in the frustrated Heisenberg magnet NaCrO$_2$. https://doi.org/10.1103/physrevb.106.054407

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