Intra-cell dynamics and cyclotron motion without magnetic field

TL;DR

This paper reveals that quantum materials with anomalous Hall effects exhibit circulating currents and cyclotron motion without magnetic fields, driven by intra-cell wavefunction dynamics, leading to observable light emission and intrinsic decay phenomena.

Contribution

It demonstrates the existence of cyclotron motion and circulating currents in anomalous Hall materials without magnetic fields, linked to intra-cell wavefunction dynamics.

Findings

Circulating currents can emit circularly polarized light pulses.

Cyclotron motion exhibits a characteristic power law decay.

Intra-cell dynamics can be probed via light emission.

Abstract

Intra-cell motion endows rich non-trivial phenomena to a wide variety of quantum materials. The most prominent example is a transverse current in the absence of a magnetic field (i.e. the anomalous Hall effect). Here we show that, in addition to a dc Hall effect, anomalous Hall materials possess circulating currents and cyclotron motion without magnetic field. These are generated from the intricate wavefunction dynamics within the unit cell, and correspond to interband transitions (coherences) in much the same way that cyclotron resonances arise from inter-Landau level transitions in magneto-optics. Curiously, anomalous cyclotron motion exhibits an intrinsic decay in time (even in pristine materials) displaying a characteristic power law decay. This reveals an intrinsic dephasing similar to that of inhomogeneous broadening of spinors. Circulating currents can manifest as the emission of circularly polarized light pulses in response to incident linearly polarized (pulsed) electric field, and provide a direct means of interrogating the intra-unit-cell dynamics of quantum materials.