Conductance asymmetries in mesoscopic superconducting devices due to finite bias

Tunneling conductance spectroscopy in normal metal-superconductor junctions is an important tool for probing Andreev bound states in mesoscopic superconducting devices, such as Majorana nanowires. In an ideal superconducting device, the subgap conductance obeys specific symmetry relations, due to particle-hole symmetry and unitarity of the...

Symmetries and Boundary Conditions of Topological Materials: General Theory and Applications

Breakdown of the Law of Reflection at a Disordered Graphene Edge

The law of reflection states that smooth surfaces reflect waves specularly, thereby acting as a mirror. This law is insensitive to disorder as long as its length scale is smaller than the wavelength. Monolayer graphene exhibits a linear dispersion at low energies and consequently a diverging Fermi wavelength. We present proof that for a...

Platform for nodal topological superconductors in monolayer molybdenum dichalcogenides

We propose a platform to realize nodal topological superconductors in a superconducting monolayer of MoX2(X=S,Se,Te) using an in-plane magnetic field. The bulk nodal points appear where the spin splitting due to spin-orbit coupling vanishes near the ±K valleys of the Brillouin zone and are six or twelve per valley in total. In the nodal...

Qsymm: Algorithmic symmetry finding and symmetric Hamiltonian generation

Symmetry is a guiding principle in physics that allows us to generalize conclusions between many physical systems. In the ongoing search for new topological phases of matter, symmetry plays a crucial role by protecting topological phases. We address two converse questions relevant to the symmetry classification of systems: is it possible to...

Andreev rectifier: A nonlocal conductance signature of topological phase transitions

The proximity effect in hybrid superconductor-semiconductor structures, crucial for realizing Majorana edge modes, is complicated to control due to its dependence on many unknown microscopic parameters. In addition, defects can spoil the induced superconductivity locally in the proximitized system, which complicates measuring global...