Impurity Moments Conceal Low-Energy Relaxation of Quantum Spin Liquids

A. Pustogow; T. Le; H. -H. Wang; Yongkang Luo; E. Gati; H. Schubert; M. Lang; S. E. Brown

doi:10.1103/PhysRevB.101.140401

Impurity Moments Conceal Low-Energy Relaxation of Quantum Spin Liquids

Strongly Correlated Electrons 2020-04-08 v1

Authors: A. Pustogow , T. Le , H. -H. Wang , Yongkang Luo , E. Gati , H. Schubert , M. Lang , S. E. Brown

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Abstract

We scrutinize the magnetic properties of $\kappa$ -(BEDT-TTF) $_2$ Hg(SCN) $_2$ Cl through its first-order metal-insulator transition at $T_{\rm CO}=30$ K by means of $^1$ H nuclear magnetic resonance (NMR). While in the metal we find Fermi-liquid behavior with temperature-independent $(T_1T)^{-1}$ , the relaxation rate exhibits a pronounced enhancement when charge order sets in. The NMR spectra remain unchanged through the transition and no magnetic order stabilizes down to 25 mK. Similar to the isostructural spin-liquid candidates $\kappa$ -(BEDT-TTF) $_2$ Cu $_2$ (CN) $_3$ and $\kappa$ -(BEDT-TTF) $_2$ Ag $_2$ (CN) $_3$ , $T_1^{-1}$ acquires a dominant maximum (here around 5 K). Field-dependent experiments identify the low-temperature feature as a dynamic inhomogeneity contribution that is typically dominant over the intrinsic relaxation but gets suppressed with magnetic field.

Keywords

quantum spin liquids impurity moments nuclear magnetic resonance charge order dynamic inhomogeneity bedt-ttf salts

Cite

@article{arxiv.1911.02057,
  title  = {Impurity Moments Conceal Low-Energy Relaxation of Quantum Spin Liquids},
  author = {A. Pustogow and T. Le and H. -H. Wang and Yongkang Luo and E. Gati and H. Schubert and M. Lang and S. E. Brown},
  journal= {arXiv preprint arXiv:1911.02057},
  year   = {2020}
}

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6 pages, 4 figures; Supplemental Material: 3 pages, 2 figures, 1 table

Impurity Moments Conceal Low-Energy Relaxation of Quantum Spin Liquids

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