Magnet-superconductor hybrid quantum systems: a materials platform for topological superconductivity

TL;DR

This review discusses magnet-superconductor hybrid systems as promising platforms for topological superconductivity, emphasizing atomic-level insights from STM studies and models to identify Majorana modes for quantum computing.

Contribution

It provides a comprehensive overview of atomic-scale investigations and categorization of hybrid systems relevant to topological superconductivity and Majorana modes.

Findings

STM and tight-binding models reveal emergent electronic properties.

Systematic categorization aids in identifying topological phases.

Focus on 1D and 2D magnetic systems proximitized to s-wave superconductors.

Abstract

Magnet-superconductor hybrid (MSH) systems have recently emerged as one of the most significant developments in condensed matter physics. This has generated, in the last decade, a steadily rising interest in the understanding of their unique properties. They have been proposed as one of the most promising platforms for the establishment of topological superconductivity, which holds high potential for application in future quantum information technologies. Scanning tunneling microscopy (STM) and spectroscopy (STS) plays a crucial role in the race to unveil the fundamental origin of the unique properties of MSH systems, with the aim to discover new hybrid quantum materials capable of hosting topologically non-trivial unconventional superconducting phases. In particular, the combination of STM studies with tight-binding model calculations have represented, so far, the most successful approach to unveil and explain the emergent electronic properties of MSHs. The scope of this review is to offer a broad perspective on the field of MSHs from an atomic-level investigation point-of-view. The focus is on discussing the link between the magnetic ground state hosted by the hybrid system and the corresponding emergent superconducting phase. This is done for MSHs with both one-dimensional (atomic chains) and two-dimensional (atomic lattices and thin films) magnetic systems proximitized to conventional s-wave superconductors. We present a systematic categorization of the experimentally investigated systems with respect to defined experimentally accessible criteria to verify or falsify the presence of topological superconductivity and Majorana edge modes. Given the vast number of publications on the topic, we limit ourselves to discuss works which are most relevant to the search for topological superconductivity.