CsV$_3$Sb$_5$中超导序参量的非平衡弛豫动力学

中文摘要 AI 辅助

时变应变场的施加驱动超导序参量偏离平衡态。序参量弛豫回平衡的方式既取决于超导能隙的结构，也取决于准粒子散射的性质。我们报道在kagome超导体CsV$_3$Sb$_5$的超导态内部发现了一个超声衰减峰。该峰是序参量弛豫时间在$T_{\ m c}$附近与超声驱动频率相匹配的自然结果。根据所测得的峰的频率依赖性，我们提取出一个微观散射时间$\ au_N = 25$ ps。这一时间尺度比由电阻率测量确定的弹性散射时间长两个数量级，但与由热输运确定的非弹性散射时间相当。在序参量弛豫的常规框架内，这意味着弹性散射对超导凝聚体的弛豫无效，这与满足安德森定理的保号$s$波态一致。

英文摘要

The application of a time-varying strain field drives a superconducting order parameter out of equilibrium. How the order parameter relaxes back to equilibrium depends both on the structure of the superconducting gap and on the nature of quasiparticle scattering. We report the discovery of an ultrasonic attenuation peak inside the superconducting state of the kagome superconductor CsV$_3$Sb$_5$. This peak is the natural consequence of the order parameter relaxation time matching the ultrasonic drive frequency near $T_{\rm c}$. From the measured frequency dependence of the peak, we extract a microscopic scattering time of $τ_N = 25$ ps. This timescale is two orders of magnitude longer than the elastic scattering time as determined by resistivity measurements, but is comparable to the inelastic scattering time determined by thermal transport. Within the conventional framework of order-parameter relaxation, this implies that elastic scattering is ineffective at relaxing the superconducting condensate, consistent with a sign-preserving $s$-wave state obeying Anderson's theorem.

发表机构

• Cornell University（康奈尔大学）
• University of California Santa Barbara（加州大学圣塔芭芭拉分校）
• Canadian Institute for Advanced Research（加拿大高等研究院）

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