Department of Physics, National Taiwan University, Taipei 10617, Taiwan.; Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan.
Department of Physics, National Taiwan University, Taipei 10617, Taiwan.; Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan.; Nano Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei 11529, Taiwan.
Sci Adv. 2016 Nov 23;2(11):e1600894. doi: 10.1126/sciadv.1600894. eCollection 2016 Nov.
The search for topological superconductors (TSCs) is one of the most urgent contemporary problems in condensed matter systems. TSCs are characterized by a full superconducting gap in the bulk and topologically protected gapless surface (or edge) states. Within each vortex core of TSCs, there exists the zero-energy Majorana bound states, which are predicted to exhibit non-Abelian statistics and to form the basis of the fault-tolerant quantum computation. To date, no stoichiometric bulk material exhibits the required topological surface states (TSSs) at the Fermi level () combined with fully gapped bulk superconductivity. We report atomic-scale visualization of the TSSs of the noncentrosymmetric fully gapped superconductor PbTaSe. Using quasi-particle scattering interference imaging, we find two TSSs with a Dirac point at ≅ 1.0 eV, of which the inner TSS and the partial outer TSS cross , on the Pb-terminated surface of this fully gapped superconductor. This discovery reveals PbTaSe as a promising candidate for TSC.
寻找拓扑超导体(TSC)是凝聚态系统中最紧迫的当代问题之一。TSC 的特征是体相全超导能隙和拓扑保护的无能隙表面(或边缘)态。在 TSC 的每个涡旋核中,存在零能马约拉纳束缚态,它们被预测表现出非阿贝尔统计,并构成容错量子计算的基础。迄今为止,没有化学计量的体材料在费米能级 () 处表现出与完全能隙超导相结合的所需拓扑表面态(TSS)。我们报告了非中心对称完全能隙超导体 PbTaSe 的 TSS 的原子尺度可视化。使用准粒子散射干涉成像,我们在这个完全能隙超导体的 Pb 终止表面上发现了两个具有狄拉克点在 ≅ 1.0 eV 的 TSS,其中内 TSS 和部分外 TSS 穿过。这一发现揭示了 PbTaSe 作为 TSC 的有前途的候选材料。