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

TL;DR

This study demonstrates nearly quantized conductance plateaus in vortex zero modes of FeTe0.55Se0.45, providing strong evidence for Majorana zero modes and highlighting their potential for topological quantum computing.

Contribution

It reports the first observation of conductance plateaus near 2e2/h in vortex zero modes of an iron-based superconductor, supporting the existence of Majorana zero modes.

Findings

Conductance plateaus close to 2e2/h observed in vortex zero modes.

No such plateaus observed in finite energy bound states.

Supports Majorana zero modes in FeTe0.55Se0.45 superconductor.

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.