论文标题
在大部分NB0.25BI2SE3中
Time-reversal invariant and fully gapped unconventional superconducting state in the bulk of the topological Nb0.25Bi2Se3
论文作者
论文摘要
最近，NIOBIUM（NB）的拓扑绝缘体BI_2SE_3，其中NB原子的有限磁矩在BI_2SE_3层之间的范Waals间隙中插入，已显示出与T_C = 3 K = 3 K和拓扑表面状态的超导性。在这里，我们报告了MUON自旋旋转实验，以探测有效的磁穿透深度lambda_eff（T）在分层拓扑超导体候选中NB_0.25BI_2SE_3中的温度依赖性。 lambda_（eff）^（-2）（t）在低温下的指数温度依赖性表明，超导转换温度t_c = 2.9 k和差距2delta/k_bt_c = 3.95（19）（19）（19）。我们还揭示了T_C/Lambda_（EFF）^（-2）的比率与非常规超导体的比率相当，后者暗示了一种非常规配对机制。此外，通过敏感的零场MUSR实验，在超导状态下排除了时间逆向对称性破裂。我们希望目前的结果将刺激理论研究，以获得对超导性与NB_0.25BI_2SE_3的超导性与拓扑非平地电子结构之间关系的理解。
Recently, the niobium (Nb)-doped topological insulator Bi_2Se_3, in which the finite magnetic moments of the Nb atoms are intercalated in the van der Waals gap between the Bi_2Se_3 layers, has been shown to exhibit both superconductivity with T_c = 3 K and topological surface states. Here we report on muon spin rotation experiments probing the temperature-dependent of effective magnetic penetration depth Lambda_eff(T) in the layered topological superconductor candidate Nb_0.25Bi_2Se_3. The exponential temperature dependence of lambda_(eff)^(-2)(T) at low temperatures suggests a fully gapped superconducting state in the bulk with the superconducting transition temperature T_c = 2.9 K and the gap to T_c ratio 2Delta/k_BT_c = 3.95(19). We also revealed that the ratio T_c/lambda_(eff)^(-2) is comparable to those of unconventional superconductors, which hints at an unconventional pairing mechanism. Furthermore, time reversal symmetry breaking was excluded in the superconducting state with sensitive zero-field muSR experiments. We hope the present results will stimulate theoretical investigations to obtain a microscopic understanding of the relation between superconductivity and the topologically non-trivial electronic structure of Nb_0.25Bi_2Se_3.
