Robust and clean Majorana zero mode in the vortex core of high-temperature superconductor (Li0.84Fe0.16)OHFeSe

TL;DR

This paper reports the observation of a robust Majorana zero mode in the vortex cores of a high-temperature superconductor, (Li0.84Fe0.16)OHFeSe, using scanning tunneling spectroscopy, highlighting its potential for topological quantum computing.

Contribution

It demonstrates the existence of a clean, well-separated Majorana zero mode in a high-temperature superconductor with topological surface states, advancing the understanding of MZMs in practical materials.

Findings

Zero-bias conductance peak (ZBCP) observed in vortex cores.

Topological surface states confirmed by ARPES and band calculations.

ZBCP attributed to Majorana zero mode from topological surface states.

Abstract

The Majorana fermion, which is its own anti-particle and obeys non-abelian statistics, plays a critical role in topological quantum computing. It can be realized as a bound state at zero energy, called a Majorana zero mode (MZM), in the vortex core of a topological superconductor, or at the ends of a nanowire when both superconductivity and strong spin orbital coupling are present. A MZM can be detected as a zero-bias conductance peak (ZBCP) in tunneling spectroscopy. However, in practice, clean and robust MZMs have not been realized in the vortices of a superconductor, due to contamination from impurity states or other closely-packed Caroli-de Gennes-Matricon (CdGM) states, which hampers further manipulations of Majorana fermions. Here using scanning tunneling spectroscopy, we show that a ZBCP well separated from the other discrete CdGM states exists ubiquitously in the cores of free vortices in the defect free regions of (Li0.84Fe0.16)OHFeSe, which has a superconducting transition temperature of 42 K. Moreover, a Dirac-cone-type surface state is observed by angle-resolved photoemission spectroscopy, and its topological nature is confirmed by band calculations. The observed ZBCP can be naturally attributed to a MZM arising from this chiral topological surface states of a bulk superconductor. (Li0.84Fe0.16)OHFeSe thus provides an ideal platform for studying MZMs and topological quantum computing.