Weyl-Majorana solenoid

Abstract

A Weyl semimetal wire with an axial magnetization has metallic surface states (Fermi arcs) winding along its perimeter, connecting bulk Weyl cones of opposite topological charge (Berry curvature). We investigate what happens to this "Weyl solenoid" if the wire is covered with a superconductor, by determining the dispersion relation of the surface modes propagating along the wire. Coupling to the superconductor breaks up the Fermi arc into a pair of Majorana modes, separated by an energy gap. Upon variation of the coupling strength along the wire there is a gap inversion that traps the Majorana fermions.

6 pages, 6 figures; V2: added discussion of charge operator, updated figures; V3: added a section on analytical mode-matching calculations, an appendix, and three new figures. To be published in the Focus Issue on "Topological semimetals" of New Journal of Physics