Observation of robust zero-energy state and enhanced superconducting gap in a tri-layer heterostructure of MnTe/Bi2Te3/Fe(Te, Se)

TL;DR

This study reports the synthesis of a tri-layer heterostructure combining superconductivity, magnetism, and strong spin-orbit coupling, revealing robust zero-energy states and an enhanced superconducting gap, indicating potential for topological superconductivity.

Contribution

The paper demonstrates the fabrication and characterization of a novel MnTe/Bi2Te3/Fe(Te, Se) heterostructure with unique zero-energy states and enhanced gaps, advancing the exploration of topological superconductivity.

Findings

Robust zero-energy states observed on 1UC MnTe surface.

Enhanced superconducting gap detected on 1UC MnTe.

First-principle calculations indicate large DMI and frustrated AFM in 1UC MnTe.

Abstract

The interface between magnetic material and superconductors has long been predicted to host unconventional superconductivity, such as spin-triplet pairing and topological nontrivial pairing state, particularly when spin-orbital coupling (SOC) is incorporated. To identify these novel pairing states, fabricating homogenous heterostructures which contain such various properties are preferred, but often challenging. Here we synthesized a tri-layer type van-der Waals heterostructure of MnTe/Bi2Te3/Fe(Te, Se), which combined s-wave superconductivity, thickness dependent magnetism and strong SOC. Via low-temperature scanning tunneling microscopy (STM), we observed robust zero-energy states with notably nontrivial properties and an enhanced superconducting gap size on single unit-cell (UC) MnTe surface. In contrast, no zero-energy state was observed on 2UC MnTe. First-principle calculations further suggest the 1UC MnTe has large interfacial Dzyaloshinskii-Moriya interaction (DMI) and a frustrated AFM state, which could promote non-collinear spin textures. It thus provides a promising platform for exploring topological nontrivial superconductivity.