纯向列量子临界超导体中的扩展奇异金属区
Extended strange metal regime in a pure nematic quantum critical superconductor
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- University of Tokyo（东京大学）
- University of Toronto（多伦多大学）
- Flatiron Institute（平顿研究所）
- Hirosaki University（弘前大学）
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中文总结 AI 辅助
本研究通过高脉冲磁场实验，在非磁性FeSe$_{1-x}$Te$_{x}$中发现纯向列量子临界点扩展出的奇异金属区，其超导性由向列临界涨落与无序协同增强，与FeSe$_{1-x}$S$_{x}$的量子临界扇形形成对比。
中文摘要 AI 辅助
高温超导性通常源于奇异金属态，在该态中，电阻率在异常宽的温度范围内表现出线性温度依赖关系。普遍认为，磁临界涨落导致奇异金属性，并提高超导转变温度。在此，利用高脉冲磁场，我们揭示了隐藏在非磁性FeSe$_{1-x}$Te$_{x}$超导穹顶之下的奇异金属基态，该体系具有纯电子向列性的量子临界点（QCP），其特征是自发旋转对称性破缺。与传统量子临界性不同，这种奇异金属态并非出现在奇异量子临界点之上的扇形区域，而是跨越了广泛的组分范围，在该范围内，配对相互作用被非磁性向列临界涨落增强。这与更纯净的FeSe$_{1-x}$S$_{x}$体系形成鲜明对比，后者在向列量子临界点之上显示出量子临界扇形区，表明无序引起的向列涨落空间随机性可能将FeSe$_{1-x}$Te$_{x}$的量子临界点扩展为临界区域，正如相关混合量子蒙特卡罗模拟所建议的那样。这些观察结果突显了纯向列临界涨落、奇异金属性和无序之间独特相互作用所促进的超导性，为各种关联材料中非费米液体输运的出现提供了新见解。
英文摘要
High-temperature superconductivity often emerges from a strange metallic state, where the electrical resistivity exhibits a linear-in-temperature dependence over an anomalously extended temperature range. The prevailing belief is that magnetic critical fluctuations gives rise to strange metallicity, enhancing the superconducting transition temperature. Here, using high pulsed magnetic fields, we have uncovered the strange metallic ground state hidden below the superconducting dome of nonmagnetic FeSe$_{1-x}$Te$_{x}$, which harbors a quantum critical point (QCP) of pure electronic nematicity, characterized by spontaneous rotational symmetry breaking. Unlike the conventional quantum criticality, this strange metallic state does not appear in a fan-shaped region above the singular QCP but spans a wide compositional range, where pairing interactions are strengthened by nonmagnetic nematic critical fluctuations. This stands in sharp contrast to the much cleaner system FeSe$_{1-x}$S$_{x}$, which displays a quantum critical fan above nematic QCP, indicating that disorder-induced spatial randomness of the nematic fluctuations likely enlarges the QCP of FeSe$_{1-x}$Te$_{x}$ into an extended region of criticality, as suggested by relevant hybrid Quantum Monte Carlo simulations. These observations highlight superconductivity promoted by a unique interplay between pure nematic critical fluctuations, strange metallicity and disorder, providing new insight into the emergence of non-Fermi-liquid transport in various correlated materials.
