Chern mosaic - topology of chiral superconductivity on ferromagnetic adatom lattices

TL;DR

This paper investigates the topological phases of superconducting surfaces with ferromagnetic adatom lattices, revealing a complex Chern mosaic pattern with high Chern numbers due to long-range hopping and spin-orbit coupling.

Contribution

It introduces the concept of a Chern mosaic in ferromagnetic adatom lattices with Rashba spin-orbit coupling, highlighting the rich topological phase diagram with high Chern numbers.

Findings

Identification of a Chern mosaic pattern in the phase diagram.

Dependence of topological phases on lattice geometry and parameters.

Establishment of the system as a versatile platform for topological matter.

Abstract

In this work we will explore the properties of superconducting surfaces decorated by two-dimensional ferromagnetic adatom lattices. As discovered recently [R\"ontynen and Ojanen, Phys. Rev. Lett. \textbf{114}, 236803 (2015)], in the presence of a Rashba spin-orbit coupling these systems may support topological superconductivity with complex phase diagrams and high Chern numbers. We show how the long-range hopping nature of the effective low-energy theory generically gives rise to a phase diagram covered by a \emph{Chern mosaic} -- a rich pattern of topological phases with large Chern numbers. We study different lattice geometries and the dependence of energy gaps and abundance of different phases as a function of system parameters. Our findings establish the studied system as one of the richest platforms for topological matter known to date.