Higher-order Weyl superconductors with anisotropic Weyl-point connectivity

TL;DR

This paper introduces higher-order Weyl superconductors realized via periodic driving in odd-parity topological superconductors, revealing anisotropic Majorana arc connectivity and new topological features.

Contribution

It demonstrates the realization of higher-order Weyl superconductors with unique Majorana arc connectivity due to higher-order topology and periodic driving.

Findings

Higher-order Weyl points separate different topological phases.

Surface projections connect via both surface and hinge Majorana arcs.

Weyl-point connectivity is anisotropic and characteristic of higher-order Weyl materials.

Abstract

Weyl superconductors feature Weyl points at zero energy in the three-dimensional (3D) Brillouin zone and arc states that connect the projections of these Weyl points on the surface. We report that higher-order Weyl superconductors can be realized in odd-parity topological superconductors with time-reversal symmetry being broken by periodic driving. Different from conventional Weyl points, the higher-order Weyl points in the bulk separate 2D first- and second-order topological phases, while on the surface, their projections are connected not only by conventional surface Majorana arcs, but also by hinge Majorana arcs. We show that the Weyl-point connectivity via Majorana arcs is largely enriched by the underlying higher-order topology and becomes anisotropic with respect to surface orientations. We identify the anisotropic Weyl-point connectivity as a characteristic feature of higher-order Weyl materials. As each 2D subsystem can be singled out by fixing the periodic driving, we propose how the Majorana zero modes in the 2D higher-order topological phases can be detected and manipulated in experiments.