Evidence for Helical Hinge Zero Modes in an Fe-Based Superconductor
Evidence for Helical Hinge Zero Modes in an Fe-Based Superconductor
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DOI：
10.1021/acs.nanolett.9b00844
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发表时间：
2019-08-01
期刊：
影响因子：
10.8
通讯作者：
Burch, K. S.
中科院分区：
文献类型：
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作者：
Gray, Mason J.;Freudenstein, Josef;Burch, K. S.
结合拓扑学和超导性为研究基础物理提供了一个强大的工具，也为容错量子计算提供了一条途径。越来越多的证据表明铁基超导体FeTe0.55Se0.45（FTS）也可能是拓扑非平凡的。如果超导阶数为s（+/-），则FTS可能是具有螺旋铰链零模（HHZMs）的高阶拓扑超导体。为了测试这些模式的存在，我们已经制造了正常的金属/超导体结通过二维原子晶体异质结在不同的表面上。正如预期的那样，与铰链接触的结揭示了一个尖锐的零偏置异常，这是不存在的隧道时，纯粹进入c轴。此外，形状和抑制与温度是一致的高度相干模式沿着铰链和不协调的零偏置异常的其他来源。在具有各种Fe间隙含量的散装样品中的软点接触的额外测量表明所观察到的模式的固有性质。因此，我们提供的证据表明，FTS确实是一个高阶拓扑超导体。
Combining topology and superconductivity provides a powerful tool for investigating fundamental physics as well as a route to fault-tolerant quantum computing. There is mounting evidence that the Fe-based superconductor FeTe0.55Se0.45 (FTS) may also be topologically nontrivial. Should the superconducting order be s(+/-), then FTS could be a higher order topological superconductor with helical hinge zero modes (HHZMs). To test the presence of these modes, we have fabricated normal-metal/superconductor junctions on different surfaces via 2D atomic crystal heterostructures. As expected, junctions in contact with the hinge reveal a sharp zero bias anomaly that is absent when tunneling purely into the c-axis. Additionally, the shape and suppression with temperature are consistent with highly coherent modes along the hinge and are incongruous with other origins of zero bias anomalies. Additional measurements with soft-point contacts in bulk samples with various Fe interstitial contents demonstrate the intrinsic nature of the observed mode. Thus, we provide evidence that FTS is indeed a higher order topological superconductor.