Evidence for an edge supercurrent in the Weyl superconductor MoTe2

Pairs on the edge Many materials with topologically nontrivial band structures are characterized by currents that run around the edge of the sample and typically consist of single excitations. It is an open question whether a topological material that is also a superconductor can support an edge current that consists of paired excitations. W. Wang et al. studied the Weyl superconductor molybdenum ditelluride and, using systematic transport measurements in the presence of a magnetic field, revealed the signatures of an edge supercurrent. Science, this issue p. 534 Systematic transport measurements in the presence of a magnetic field indicate paired excitations in the edge current. Edge supercurrents in superconductors have long been an elusive target. Interest in them has reappeared in the context of topological superconductivity. We report evidence for the existence of a robust edge supercurrent in the Weyl superconductor molybdenum ditelluride (MoTe2). In a magnetic field B, fluxoid quantization generates a periodic modulation of the edge condensate observable as a “fast-mode” oscillation of the critical current Ic versus B. The fast-mode frequency is distinct from the conventional Fraunhofer oscillation displayed by the bulk supercurrent. We confirm that the fast-mode frequency increases with crystal area as expected for an edge supercurrent. In addition, weak excitation branches are resolved that display an unusual broken symmetry.