Impurity-induced excitations in a topological two-dimensional ferromagnet/superconductor van der Waals moir\'e heterostructure

TL;DR

This paper investigates how non-magnetic impurities affect the spectral and topological properties of topological superconductors in van der Waals heterostructures with moire patterns, revealing complex impurity-length scale interactions.

Contribution

It provides a detailed analysis of impurity effects on topological moire superconductors, highlighting the interplay between impurity placement, moire length, and topological properties.

Findings

Impurities cause significant changes in spectral properties depending on their position.

The impurity effects are strongly influenced by the moire length scale.

Impurities can induce topological transitions in the system.

Abstract

The emergence of a topological superconducting state in van der Waals heterostructures provides a new platform for exploring novel strategies to control topological superconductors. In particular, impurities in van der Waals heterostructures, generically featuring a moire pattern, can potentially lead to the unique interplay between atomic and moire length scales, a feature absent in generic topological superconductors. Here we address the impact of non-magnetic impurities on a topological moire superconductor, both in the weak and strong regime, considering both periodic arrays and single impurities in otherwise pristine infinite moire systems. We demonstrate a fine interplay between impurity-induced modes and the moire length, leading to radically different spectral and topological properties depending on the relative impurity location and moire lengths. Our results highlight the key role of impurities in van der Waals heterostructures featuring moire patterns, revealing the key interplay between length and energy scales in artificial moire systems.