中国科学院物理研究所陈其宏、金魁团队近日取得一项新成果。经过不懈努力，他们发现了FeSe中超导与奇异金属态之间的相互作用。2023年1月16日，国际知名学术期刊《自然—物理学》发表了这一成果。
研究人员报道了在FeSe中观察到的一个典型的奇异金属行为，即T-线性电阻率、线性场磁电阻和磁电阻的普适标度。更重要的是，当研究人员通过离子液体门控调节超导时，超导转变温度从大约10 K增加到45 K, T线性电阻率系数表现出与临界温度的二次依赖关系。这是一个普遍存在的特征，描述了这些参数在各种系统之间的关系，包括过度掺杂的铜酸盐和Bechgaard盐。这表明，T线电阻率和非常规超导可能存在一种普遍机制。
据介绍，传统费米液体的电阻率与温度成二次方，与之相反，非常规超导体的正常态电阻率在低温极限下是温度的线性函数(T - 线性)。这种被称为奇怪金属的现象在铜酸盐中得到了广泛的研究，并被认为与超导密切相关。因此，定量描述其与超导的关系对于进一步发展理论认识是非常重要的。但迄今为止，由于难以实现对超导态的系统控制，全面的研究非常少。
附：英文原文
Title: Interplay between superconductivity and the strange-metal state in FeSe
Author: Jiang, Xingyu, Qin, Mingyang, Wei, Xinjian, Xu, Li, Ke, Jiezun, Zhu, Haipeng, Zhang, Ruozhou, Zhao, Zhanyi, Liang, Qimei, Wei, Zhongxu, Lin, Zefeng, Feng, Zhongpei, Chen, Fucong, Xiong, Peiyu, Yuan, Jie, Zhu, Beiyi, Li, Yangmu, Xi, Chuanying, Wang, Zhaosheng, Yang, Ming, Wang, Junfeng, Xiang, Tao, Hu, Jiangping, Jiang, Kun, Chen, Qihong, Jin, Kui, Zhao, Zhongxian
Issue&Volume: 2023-01-16
Abstract: In contrast to conventional Fermi liquids where resistivity scales quadratically with temperature, unconventional superconductors usually exhibit a normal-state resistivity that varies as a linear function of temperature (T-linear) in the low-temperature limit. This phenomenon, termed as the strange metal, has been extensively studied in cuprates and is thought to be intimately linked to superconductivity. A quantitative description of its relationship with superconductivity is, therefore, of great importance for developing further theoretical understanding; however, so far, comprehensive studies are scarce due to the difficulties in realizing a systematic control of the superconducting state. Here we report the observation of a typical strange-metal behaviour in FeSe, namely, T-linear resistivity, linear-in-field magnetoresistance and universal scaling of magnetoresistance. More importantly, when we tune the superconductivity by ionic-liquid gating, the superconducting transition temperature increases from approximately 10 to 45K, and the T-linear resistivity coefficient exhibits a quadratic dependence on the critical temperature. This is a ubiquitous feature that describes the relation between these parameters in various systems including overdoped cuprates and Bechgaard salts. This suggests that there may be a universal mechanism underlying the T-linear resistivity and unconventional superconductivity.
DOI: 10.1038/s41567-022-01894-4
Source: https://www.nature.com/articles/s41567-022-01894-4