Nearly quantized conductance plateau of vortex zero mode in an iron-based superconductor

Shiyu Zhu; Lingyuan Kong; Lu Cao; Hui Chen; Michal Papaj; Shixuan Du; Yuqing Xing; Wenyao Liu; Dongfei Wang; Chengmin Shen; Fazhi Yang; John Schneeloch; Ruidan Zhong; Genda Gu; Liang Fu; Yu-Yang Zhang; Hong Ding; Hong-Jun Gao

doi:10.1126/science.aax0274

arXiv · 1904.06124

Nearly quantized conductance plateau of vortex zero mode in an iron-based superconductor

Shiyu Zhu·Lingyuan Kong·Lu Cao·Hui Chen·Michal Papaj·Shixuan Du·Yuqing Xing·Wenyao Liu·Dongfei Wang·Chengmin Shen·Fazhi Yang·John Schneeloch·Ruidan Zhong·Genda Gu·Liang Fu·Yu-Yang Zhang·Hong Ding·Hong-Jun Gao

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Abstract

Majorana zero-modes (MZMs) are spatially-localized zero-energy fractional quasiparticles with non-Abelian braiding statistics that hold a great promise for topological quantum computing. Due to its particle-antiparticle equivalence, an MZM exhibits robust resonant Andreev reflection and 2e2/h quantized conductance at low temperature. By utilizing variable-tunnel-coupled scanning tunneling spectroscopy, we study tunneling conductance of vortex bound states on FeTe0.55Se0.45 superconductors. We report observations of conductance plateaus as a function of tunnel coupling for zero-energy vortex bound states with values close to or even reaching the 2e2/h quantum conductance. In contrast, no such plateau behaviors were observed on either finite energy Caroli-de Genne-Matricon bound states or in the continuum of electronic states outside the superconducting gap. This unique behavior of the zero-mode conductance reaching a plateau strongly supports the existence of MZMs in this iron-based superconductor, which serves as a promising single-material platform for Majorana braiding at a relatively high temperature.

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Shiyu Zhu, Lingyuan Kong, Lu Cao, Hui Chen, Michal Papaj, Shixuan Du, Yuqing Xing, Wenyao Liu, Dongfei Wang, Chengmin Shen, Fazhi Yang, John Schneeloch, Ruidan Zhong, Genda Gu, Liang Fu, Yu-Yang Zhang, Hong Ding, Hong-Jun Gao. 2019-04-12. Nearly quantized conductance plateau of vortex zero mode in an iron-based superconductor. https://doi.org/10.1126/science.aax0274

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