Anomalous enhancement of the Nernst effect at the crossover between a Fermi liquid and a strange metal
Anomalous enhancement of the Nernst effect at the crossover between a Fermi liquid and a strange metal
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DOI：
10.1038/s41567-022-01904-5
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发表时间：
2023-01
期刊：
影响因子：
19.6
通讯作者：
Yusen Yang;Q. Tao;Yuqiang Fang;G. Tang;Chao Yao;Xiaoxian Yan;Chenxi Jiang;Xiangfan Xu;F. H
中科院分区：
文献类型：
--
作者：
Yusen Yang;Q. Tao;Yuqiang Fang;G. Tang;Chao Yao;Xiaoxian Yan;Chenxi Jiang;Xiangfan Xu;F. H
奇怪的金属状态出现在许多强相关材料中，因此了解它的性质是凝聚态物理中的一个关键问题。这种知识可以为高温超导性和量子临界性提供重要的见解，但标准费米液体理论在奇怪的金属中不起作用。建立一个替代理论一直是一个长期的挑战，而且奇怪金属的基本方面——包括它们的载流子的性质——仍然难以捉摸。在这里，我们报告了在二维超导体2M-WS2的奇异金属态中观察到的大能思特响应。具体来说，当系统从费米-液态进入奇异金属态时，能思特系数增加到与超导铜铜中的涡旋能思特信号相当，并且对载流子迁移率高度敏感。能思特峰对温度和磁场的依赖性排除了朗道准粒子和超导性的相关性。相反，交叉处的能态峰表示进入奇异金属态时载流子熵的变化。这种反常能思特响应的存在在其他标志性的奇异金属中得到了进一步的证实，表明了其普遍性，并对奇异金属的机制提出了实验约束。
A strange-metal state appears in many strongly correlated materials, so understanding its nature is a crucial problem in condensed matter physics. This knowledge could provide important insight into high-temperature superconductivity and quantum criticality, but standard Fermi-liquid theory fails in strange metals. Establishing an alternative theory has been a long-standing challenge and fundamental aspects of strange metals—including the nature of their charge carriers—remain elusive. Here we report the observation of a large Nernst response in the strange-metal state in a two-dimensional superconductor 2M-WS2. Specifically, when the system enters the strange-metal state from the Fermi-liquid state, the Nernst coefficient increases to be comparable to the vortex Nernst signal in superconducting cuprates, and it is highly sensitive to carrier mobility. The temperature and magnetic field dependence of the Nernst peak rule out the relevance of both Landau quasiparticles and superconductivity. Instead, the Nernst peak at the crossover indicates a change in carrier entropy when entering the strange-metal state. The presence of such an anomalous Nernst response is further confirmed in other iconic strange metals, suggesting its universality and places experimental constraints on the mechanism of strange metals.