Zero-energy vortex bound state in the superconducting topological surface state of Fe(Se,Te)
Zero-energy vortex bound state in the superconducting topological surface state of Fe(Se,Te)
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DOI：
10.1038/s41563-019-0397-1
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发表时间：
2019-08-01
期刊：
影响因子：
41.2
通讯作者：
Tamegai, T.
中科院分区：
文献类型：
--
作者：
Machida, T.;Sun, Y.;Tamegai, T.
凝聚态物质中的马约拉纳准粒子对于拓扑量子计算很重要(1-3)，但仍然难以捉摸。拓扑超导体的涡核可以容纳在零能量下表现为马约拉纳束缚态（MBS）的马约拉纳准粒子(4,5)。铁基超导体 Fe(Se,Te) 具有超导拓扑表面态 (6-9)，通过扫描隧道显微镜 (STM) 研究表明存在这种零能量涡旋束缚态 (ZVBS)(10,11)。在这里，我们提出了超高能量分辨率光谱成像（SI）-STM，以阐明 Fe（Se，Te）中涡旋束缚态的性质。我们发现 ZVBS 位于 0 +/- 20 mu eV，这限制了其 MBS 起源，并表明一些涡流存在 ZVBS，但其他涡流则不然。我们表明，承载 ZVBS 的涡流比例随着磁场的增加而减少，并且局部淬灭紊乱与 ZVBS 无关。我们的观察阐明了实现 ZVBS 的必要条件，这为可控马约拉纳准粒子铺平了道路。
Majorana quasiparticles in condensed matter are important for topological quantum computing(1-3), but remain elusive. Vortex cores of topological superconductors may accommodate Majorana quasiparticles that appear as the Majorana bound state (MBS) at zero energy(4,5). The iron-based superconductor Fe(Se,Te) possesses a superconducting topological surface state(6-9) that was investigated by scanning tunnelling microscopy (STM) studies, which suggest such a zero-energy vortex bound state (ZVBS)(10,11). Here we present ultrahigh energy-resolution spectroscopic imaging (SI)-STM to clarify the nature of the vortex bound states in Fe(Se,Te). We found the ZVBS at 0 +/- 20 mu eV, which constrained its MBS origin, and showed that some vortices host the ZVBS but others do not. We show that the fraction of vortices hosting the ZVBS decreases with increasing magnetic field and that local quenched disorders are not related to the ZVBS. Our observations elucidate the necessary conditions to realize the ZVBS, which paves the way towards controllable Majorana quasiparticles.