Strain manipulation of Majorana fermions in graphene armchair nanoribbons

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 $0.1\mathrm{\%}$. 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.