Anomalous Hall effect in semiconductor quantum wells in proximity to chiral p-wave superconductors

TL;DR

This paper investigates the microscopic origins of the anomalous Hall effect in chiral p-wave superconductors, revealing the roles of impurity scattering, nonlinear optical excitation, and broken Galilean invariance in generating Hall currents.

Contribution

It introduces a gauge-invariant kinetic approach to distinguish intrinsic and extrinsic Hall effects, uncovering a novel impurity-independent induction channel due to particle-hole asymmetry.

Findings

Intrinsic Hall conductivity is zero without broken Galilean invariance.

Extrinsic Hall current arises from impurity scattering and optical excitation.

A new induction channel dominates in weak impurity regimes.

Abstract

By using the gauge-invariant optical Bloch equation, we perform a microscopic kinetic investigation on the anomalous Hall effect in chiral p-wave superconducting states. Specifically, the intrinsic anomalous Hall conductivity in the absence of the magnetic field is zero as a consequence of Galilean invariance in our description. As for the extrinsic channel, a finite anomalous Hall current is obtained from the impurity scattering with the optically excited normal quasiparticle current even at zero temperature. From our kinetic description, it can be clearly seen that the excited normal quasiparticle current is due to an induced center-of-mass momentum of Cooper pairs through the acceleration driven by ac electric field. For the induced anomalous Hall current, we show that the conventional skew-scattering channel in the linear response makes the dominant contribution in the strong impurity interaction. In this case, our kinetic description as a supplementary viewpoint mostly confirms the results of Kubo formalism in the literature. Nevertheless, in the weak impurity interaction, this skew-scattering channel becomes marginal and we reveal that a novel induction channel from the Born contribution dominates the anomalous Hall current. This novel channel, which has long been overlooked in the literature, is due to the particle-hole asymmetry by nonlinear optical excitation. Finally, we study the case in the chiral p-wave superconducting state with a transverse conical magnetization, which breaks the Galilean invariance. In this situation, the intrinsic anomalous Hall conductivity is no longer zero. Comparison of this intrinsic channel with the extrinsic one from impurity scattering is addressed.