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arXiv · 1907.02847

Spinon Excitations in the Quasi-1D S = 1/2 Chain Cs4CuSb2Cl12

Thao T. Tran·Chris A. Pocs·Yubo Zhang·Michal J. Winiarski·Jianwei Sun·Minhyea Lee·Tyrel M. McQueen
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Abstract

The spin-1/2 Heisenberg antiferromagnetic chain is ideal for realizing one of the simplest gapless quantum spin-liquids (QSLs), supporting a many-body ground state whose elementary excitations are fractional fermionic excitations called spinons. Here we report the discovery of such a 1D QSL in Cs4CuSb2Cl12. Compared to previously reported S = 1/2 1D chains, this material possesses a wider temperature range over which the QSL state is stabilized. We identify spinon excitations extending at T > 0.8 K, with a large T-linear contribution to the specific heat, gamma = 31.5(2) mJ mol-1 K-2 which contribute itinerantly to thermal transport up to temperatures as high as T = 35 K. At T = 0.7 K, we find a second-order phase transition, suggesting a weak spin-Peierls transition that is unchanged by a 5 T magnetic field. Cs4CuSb2Cl12 reveals new phenomenology deep in the 1D QSL regime, supporting a gapped QSL phase over a wide temperature range compared to many other experimental realizations.

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Thao T. Tran, Chris A. Pocs, Yubo Zhang, Michal J. Winiarski, Jianwei Sun, Minhyea Lee, Tyrel M. McQueen. 2019-07-05. Spinon Excitations in the Quasi-1D S = 1/2 Chain Cs4CuSb2Cl12. https://doi.org/10.1103/physrevb.101.235107

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