High-resolution studies of the Majorana atomic chain platform
High-resolution studies of the Majorana atomic chain platform
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DOI：
10.1038/nphys3947
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发表时间：
2017-03-01
期刊：
影响因子：
19.6
通讯作者：
Yazdani, Ali
中科院分区：
文献类型：
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作者：
Feldman, Benjamin E.;Randeria, Mallika T.;Yazdani, Ali
传统超导体表面磁性原子的有序组装可以用于设计拓扑超导相，并在凝聚态环境中实现马约拉纳费米子准粒子（MQPs）。最近的实验表明，Pb上的铁原子链通常具有形成一维拓扑超导体所需的电子特征，并且在这种链的末端揭示了局域mqp的空间分辨特征。在这里，我们报告使用稀释冰箱扫描隧道显微镜（STM）对相同的原子链系统进行了更高分辨率的测量。与之前的研究相比，我们发现铁链中的零偏峰（ZBP）没有检测到与其他态杂化的分裂。测量结果还显示，ZBP在纳米尺度上呈现出独特的“双眼”空间模式。从理论上讲，我们表明这是超导衬底中具有大量谱重的MQPs的STM测量的一般结果，这一结论进一步得到了沉积在铁链顶部的Pb覆盖层的测量的支持。最后，我们报告了用超导尖端进行的实验，以寻找在这种测量中预期的粒子-空穴对称MQP特征。
Ordered assemblies of magnetic atoms on the surface of conventional superconductors can be used to engineer topological superconducting phases and realize Majorana fermion quasiparticles (MQPs) in a condensed matter setting. Recent experiments have shown that chains of Fe atoms on Pb generically have the required electronic characteristics to form a one-dimensional topological superconductor and have revealed spatially resolved signatures of localized MQPs at the ends of such chains. Here we report higher-resolution measurements of the same atomic chain system performed using a dilution refrigerator scanning tunnelling microscope (STM). With significantly better energy resolution than previous studies, we show that the zero-bias peak (ZBP) in Fe chains has no detectable splitting from hybridization with other states. The measurements also reveal that the ZBP exhibits a distinctive 'double eye' spatial pattern on nanometre length scales. Theoretically we show that this is a general consequence of STM measurements of MQPs with substantial spectral weight in the superconducting substrate, a conclusion further supported by measurements of Pb overlayers deposited on top of the Fe chains. Finally, we report experiments performed with superconducting tips in search of the particle-hole symmetric MQP signature expected in such measurements.