标题： 普朗克散射和铁硒基超导体FeTe$_{1-x}$Se$_x$中的平行导电通道 显示英文标题

标题： Planckian scattering and parallel conduction channels in the iron chalcogenide superconductors FeTe$_{1-x}$Se$_x$

摘要： 铜基超导体的电阻率随温度线性变化的现象，在一些样品中从$T_c$延伸到熔点，至今仍未得到解释。尽管看似简单，这种温度依赖性与金属的传统理论相矛盾，该理论指出如果电子-电子散射占主导，则散射率$1/\tau$应该是温度的二次函数。 理解这种温度依赖性的起源及其与超导性的联系，可能是揭开高温超导之谜的关键。使用时域太赫兹光谱（TDTS），我们阐明了两种 FeTe$_{1-x}$Se$_x$（FTS）样品在低温下的导电行为，一种被认为具有拓扑超导性的硒和碲含量几乎相等的样品，以及另一种过掺杂的样品。 受限于直流电阻率，我们发现存在两个并行的导电通道：一个频率范围较宽且温度依赖性较弱的通道，另一个较为尖锐且其散射率遵循普朗克极限速率$\sim kT/h$的通道。 通过分析其频谱权重，我们证明超导凝聚态主要来自于经历这种普朗克散射的通道。 显示英文摘要

摘要： The remarkable linear in temperature resistivity of the cuprate superconductors, which extends in some samples from $T_c$ to the melting temperature, remains unexplained. Although seemingly simple, this temperature dependence is incompatible with the conventional theory of metals that dictates that the scattering rate, $1/\tau$, should be quadratic in temperature if electron-electron scattering dominates. Understanding the origin of this temperature dependence and its connection to superconductivity may provide the key to pick the lock of high-temperature superconductivity. Using time-domain terahertz spectroscopy (TDTS) we elucidate the low temperature conducting behavior of two FeTe$_{1-x}$Se$_x$ (FTS) samples, one with almost equal amounts of Se and Te that is believed to be a topological superconductor, and one that is more overdoped. Constrained with DC resistivity, we find two conduction channels that add in parallel, a broad one in frequency with weak temperature dependence and a sharper one whose scattering rate goes as the Planckian limited rate, $\sim kT/h$. Through analysis of its spectral weight we show the superconducting condensate is mainly drawn from the channel that undergoes this Planckian scattering.