Complete electrodynamics of a BCS superconductor with μeV energy scales: Microwave spectroscopy on titanium at mK temperatures
Complete electrodynamics of a BCS superconductor with μeV energy scales: Microwave spectroscopy on titanium at mK temperatures
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DOI：
10.1103/physrevb.97.214516
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发表时间：
2018-06-20
影响因子：
3.7
通讯作者：
Scheffler, Marc
中科院分区：
文献类型：
--
作者：
Thiemann, Markus;Dressel, Martin;Scheffler, Marc
我们对超导钛 (Ti) 进行了谐振微波测量，温度低至 40 mK，远低于其临界温度 T-c（约 0.5 K）。我们的宽频率范围 3.3-40 GHz 包含零温能隙 2 Delta(0)，使我们能够探测超导态的完整电动力学，包括跨能隙的激励和 超流体凝聚体和热准粒子。观察到的行为遵循基于 BCS 的 Mattis-Bardeen 形式主义的预测，这意味着超导 Ti 处于肮脏极限，与我们对散射率的确定一致。我们直接确定了能隙的温度依赖性，这与 BCS 预测一致，2 Delta(0)/k(B)T(c) 近似于 3.5，Delta(0) 近似于 72 mu eV。我们还评估了穿透深度，并表征了超导钛在外部磁场中的行为。
We performed resonant microwave measurements on superconducting titanium (Ti) down to temperatures of 40 mK, well below its critical temperature T-c approximate to 0.5 K. Our wide frequency range 3.3-40 GHz contains the zero-temperature energy gap 2 Delta(0) and allows us to probe the full electrodynamics of the superconducting state, including excitations across the gap and the low-frequency responses of superfluid condensate and thermal quasiparticles. The observed behavior follows the predictions of the BCS-based Mattis-Bardeen formalism, which implies that superconducting Ti is in the dirty limit, in agreement with our determination of the scattering rate. We directly determine the temperature dependence of the energy gap, which is in accordance with BCS predictions, and 2 Delta(0)/k(B)T(c) approximate to 3.5 with Delta(0) approximate to 72 mu eV. We also evaluate the penetration depth, and we characterize the behavior of superconducting Ti in external magnetic field.