Li Yangmu, Zaki Nader, Garlea Vasile O, Savici Andrei T, Fobes David, Xu Zhijun, Camino Fernando, Petrovic Cedomir, Gu Genda, Johnson Peter D, Tranquada John M, Zaliznyak Igor A
Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY, USA.
Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
Nat Mater. 2021 Sep;20(9):1221-1227. doi: 10.1038/s41563-021-00984-7. Epub 2021 Apr 22.
The idea of employing non-Abelian statistics for error-free quantum computing ignited interest in reports of topological surface superconductivity and Majorana zero modes (MZMs) in FeTeSe. However, the topological features and superconducting properties are not observed uniformly across the sample surface. The understanding and practical control of these electronic inhomogeneities present a prominent challenge for potential applications. Here, we combine neutron scattering, scanning angle-resolved photoemission spectroscopy, and microprobe composition and resistivity measurements to characterize the electronic state of FeTeSe. We establish a phase diagram in which the superconductivity is observed only at sufficiently low Fe concentration, in association with distinct antiferromagnetic correlations, whereas the coexisting topological surface state occurs only at sufficiently high Te concentration. We find that FeTeSe is located very close to both phase boundaries, which explains the inhomogeneity of superconducting and topological states. Our results demonstrate the compositional control required for use of topological MZMs in practical applications.
将非阿贝尔统计用于无差错量子计算的想法引发了人们对FeTeSe中拓扑表面超导性和马约拉纳零模（MZMs）相关报道的兴趣。然而，在整个样品表面并非均匀地观察到拓扑特征和超导特性。对这些电子不均匀性的理解和实际控制对潜在应用构成了重大挑战。在此，我们结合中子散射、扫描角分辨光电子能谱以及微探针成分和电阻率测量来表征FeTeSe的电子态。我们建立了一个相图，其中仅在足够低的铁浓度下观察到超导性，且伴有明显的反铁磁关联，而共存的拓扑表面态仅在足够高的碲浓度下出现。我们发现FeTeSe非常接近两个相界，这解释了超导态和拓扑态的不均匀性。我们的结果证明了在实际应用中使用拓扑MZMs所需的成分控制。
