Strain manipulation of Majorana fermions in graphene armchair nanoribbons

TL;DR

This paper explores how uniaxial strain can be used to manipulate Majorana fermions in graphene armchair nanoribbons, revealing a highly sensitive topological phase transition suitable for real-space control.

Contribution

It demonstrates the strain-induced topological phase transition in graphene nanoribbons with enhanced spin-orbit coupling and Zeeman field, enabling Majorana fermion manipulation.

Findings

Topological phase transition occurs below 0.1% strain.

Strain, Zeeman field, and chemical potential can manipulate Majorana modes.

Graphene nanoribbons can host and control Majorana fermions via strain.

Abstract

Graphene nanoribbons with armchair edges are studied for externally enhanced, but realistic parameter values: enhanced Rashba spin-orbit coupling due to proximity to a transition metal dichalcogenide like WS$_{2}$, and enhanced Zeeman field due to exchange coupling with a magnetic insulator like EuS under applied magnetic field. The presence of s--wave superconductivity, induced either by proximity or by decoration with alkali metal atoms like Ca or Li, leads to a topological superconducting phase with Majorana end modes. The topological phase is highly sensitive to the application of uniaxial strain, with a transition to the trivial state above a critical strain well below $0.1\%$. This sensitivity allows for real space manipulation of Majorana fermions by applying non-uniform strain profiles. Similar manipulation is also possible by applying inhomogeneous Zeeman field or chemical potential.