Impurity moments conceal low-energy relaxation of quantum spin liquids
Impurity moments conceal low-energy relaxation of quantum spin liquids
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DOI：
10.1103/physrevb.101.140401
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发表时间：
2019-11
影响因子：
3.7
通讯作者：
A. Pustogow;T. Le;H.-H. Wang-H.;Yongkang Luo;E. Gati;H. Schubert;M. Lang;S. Brown
中科院分区：
文献类型：
--
作者：
A. Pustogow;T. Le;H.-H. Wang-H.;Yongkang Luo;E. Gati;H. Schubert;M. Lang;S. Brown
利用$^1$H核磁共振（NMR）研究了$\kappa$-(BEDT-TTF)$_2$Hg(SCN)$_2$Cl在$T_{\rm CO}=30$ K处的一阶金属-绝缘体跃迁的磁性。而在金属中，我们发现费米-液体行为具有与温度无关的$(T_1T)^{-1}$，当电荷顺序开始时，弛豫速率表现出明显的增强。与同结构自旋液体候选物$\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$和$\kappa$-(BEDT-TTF)$_2$Ag$_2$(CN)$_3$类似，$T_1^{-1}$获得优势最大值（这里约为5 K）。场相关实验表明，低温特性是一种动态非均匀性的贡献，它通常在本征弛豫中占主导地位，但被磁场抑制。
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.