Fate of Majorana modes in $\mathrm{CeCoIn}_5$/$\mathrm{YbCoIn}_5$ superlattices -a test bed for reduction of topological classification-

TL;DR

This study investigates the topological properties of CeCoIn5/YbCoIn5 superlattices, revealing how interactions can reduce the topological classification and affect Majorana edge modes, providing insights into topological superconductivity.

Contribution

It demonstrates the reduction of topological classification in superlattices due to interactions, highlighting the protection of edge modes in different layer configurations.

Findings

Quad-layer CeCoIn5 exhibits a topological crystalline superconducting phase.

Two-body interactions remove protection of edge modes in quad-layer systems.

Topological classification reduces from Z⊕Z to Z⊕Z8 due to interactions.

Abstract

In this paper, we propose $\mathrm{CeCoIn_5}/\mathrm{YbCoIn_5}$ superlattice systems as a test bed for the reduction of topological classification in free fermions. We find that the system with quad-layer of $\mathrm{CeCoIn_5}$ shows a topological crystalline superconducting phase with the mirror Chern number eight at the non-interacting level. Furthermore, we demonstrate that in the presence of two-body interactions, gapless edge modes are no longer protected by the symmetry in the system with quad-layer, but are protected in the systems with bi- or tri-layer. This clearly exemplifies the reduction of topological classification from $\mathbb{Z}\oplus\mathbb{Z}$ to $\mathbb{Z}\oplus\mathbb{Z}_8$.