Current- and field-induced topology in twisted nodal superconductors

TL;DR

This paper demonstrates that interlayer current and magnetic fields can induce topological phases in twisted bilayer nodal superconductors, leading to observable edge modes and thermal Hall effects.

Contribution

It introduces a mechanism for inducing topological superconductivity via interlayer current and magnetic fields in twisted bilayer nodal superconductors, highlighting the role of twist angle.

Findings

Bulk gap maximizes near a 'magic' twist angle.

Chiral edge modes cause quantized thermal Hall effect.

Magnetic fields create topological domain lattices with edge modes.

Abstract

We show that interlayer current induces topological superconductivity in twisted bilayers of nodal superconductors. A bulk gap opens and achieves its maximum near a ``magic'' twist angle $\theta_\mathrm{MA}$. Chiral edge modes lead to a quantized thermal Hall effect at low temperatures. Furthermore, we show that an in-plane magnetic field creates a periodic lattice of topological domains with edge modes forming low-energy bands. We predict their signatures in scanning tunneling microscopy. Estimates for candidate materials indicate that twist angles $\theta\sim \theta_\mathrm{MA}$ are optimal for observing the predicted effects.