论文标题
BI单晶中脆弱的电子超导性
Fragile electronic superconductivity in Bi Single crystal
论文作者
论文摘要
据推测，即使在超低温度（$ <$ 10 mk）的载体密度（$ \ 3 \ times10^{17} $ cm $ cm $^{ - 3} $）上，半晶子（BI）即使在超低温度（$ <$ 10 mk）也不会显示超导性（SC）。最近，我们以$ \ mathrm {t_c = 0.53} $ MK的超纯度（99.9999 \％）的BI单晶建立了大量超导性，并在[$ 0001 $]（trigonal）（trigonal）（trigonal）（trigonal）（trigonanal）（trigonal）（trigonanal）（trigonal）（trigonal）（trigonal）（trigonal）（trrigonal）（trigonal）（trrigonal）（trrigonal）（trigonal）（trrigonanal），带有外推上层临界场$ \ mathrm {h_c（0） - mathrm {t_c = 0.53} $ mk。在电荷载体的浓度非常低的情况下，我们正在处理脆弱的库珀对，估计的大相干长度$ \ mathrm {ξ_{gl}（0）（0）（0）\大约96μ} $ m。我们还指出，需要超越常规的电子音波耦合（类似BCS）机制才能了解BI中的SC态。 BI是一种补偿半金属，具有电子和孔作为电荷载体。为了找到负责SC的电荷载体，我们报告了沿[$ 01 \ bar 10 $]（Bisectrix） - 晶体学方向的各向异性临界场的温度依赖性，并将其与沿着三角形的测量结果进行了比较。我们对临界场各向异性的理论分析表明，三个BI频段的光口中的光电子负责SC，并表明BI是极弱的II型（接近I型）超导体。最后，我们回顾了当前提议解释bi中SC的理论。
It was presumed that semimetal Bismuth (Bi) would not show superconductivity (SC) even at ultra-low temperatures ($<$10 mK) due to its very low carrier density ($\approx 3\times10^{17}$cm$^{-3}$). Recently, we have established bulk superconductivity in ultra-pure (99.9999\%) Bi single crystal at $\mathrm{T_C = 0.53}$ mK with an extrapolated upper critical field $\mathrm{H_C(0) = 5.2μ}$T measured along the [$0001$] (trigonal) -crystallographic direction. At very low concentrations of the charge carriers, we are dealing with fragile Cooper pairs with an estimated large coherence length $\mathrm{ξ_{GL}(0)\approx 96 μ}$m. We also stated that one needs to go beyond the conventional electron-phonon coupling (BCS-like) mechanism to understand the SC state in Bi. Bi is a compensated semi-metal with electrons and holes as charge carriers. In order to find the charge carriers responsible for the SC, we report the temperature dependence of the anisotropic critical field along the [$01\bar 10$] (bisectrix)-crystallographic direction and compared it with the earlier data from measurements along the trigonal. Our theoretical analysis of the anisotropy of critical fields suggests that the light electrons in the three pockets of Bi bands are responsible for the SC and indicates that Bi is an extremely weak type-II (close to type-I) superconductor. Finally, we review the current theories proposed to explain the SC in Bi.
