Massive Suppression of Proximity Pairing in Topological (Bi1-xSbx)2Te3 Films on Niobium
Massive Suppression of Proximity Pairing in Topological (Bi1-xSbx)2Te3 Films on Niobium
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DOI：
10.1103/physrevlett.124.236402
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发表时间：
2020-06-12
影响因子：
8.6
通讯作者：
Chiang, T-C
中科院分区：
文献类型：
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作者：
Hlevyack, Joseph A.;Najafzadeh, Sahand;Chiang, T-C
体导体拓扑结构的Bi2Se_3薄膜与S波超导体的界面在非平凡表面态引发了强超导有序。然而，体绝缘拓扑(Bi1-xSbx)(2)Te-3薄膜在块状Nb上却表现出表面超导电性的巨大衰减，即使对于只有两层厚的薄膜也是如此。超高分辨率的能带映射以及量化的超导能隙与重掺n的Bi2Se3/Nb拓扑结构的对比证明了近邻配对的这种巨大的抑制作用。这些结果强调了利用超导邻近效应来实现近本征系统中的拓扑超导的局限性。
Interfacing bulk conducting topological Bi2Se3 films with s-wave superconductors initiates strong superconducting order in the nontrivial surface states. However, bulk insulating topological (Bi1-xSbx)(2)Te-3 films on bulk Nb instead exhibit a giant attenuation of surface superconductivity, even for films only two layers thick. This massive suppression of proximity pairing is evidenced by ultrahigh-resolution band mappings and by contrasting quantified superconducting gaps with those of heavily n-doped topological Bi2Se3/Nb. The results underscore the limitations of using superconducting proximity effects to realize topological superconductivity in nearly intrinsic systems.