Ultrafast control of moir\'e pseudo-electromagnetic field in homobilayer semiconductors

TL;DR

This paper demonstrates ultrafast control of moiré pseudo-electromagnetic fields in homobilayer semiconductors through dynamic modulation of Zeeman fields, enabling manipulation of valley and spin degrees of freedom.

Contribution

It introduces a method to dynamically control topological Zeeman textures in moiré patterns using terahertz fields or interlayer bias, a novel approach for ultrafast valley and spin manipulation.

Findings

Dynamically tunable topological Zeeman textures in moiré patterns.

Emergence of in-plane electric fields related to Berry curvature.

Potential for ultrafast valley and spin control in semiconductors.

Abstract

In long-wavelength moir\'e patterns of homobilayer semiconductors, the layer pseudospin of electrons is subject to a sizable Zeeman field that is spatially modulated from the interlayer coupling in moir\'e. By interference of this spatial modulation with a homogeneous but dynamically tunable component from out-of-plane electric field, we show that the spatial-temporal profile of the overall Zeeman field therefore features a topological texture that can be controlled in an ultrafast timescale by a terahertz field or an interlayer bias. Such dynamical modulation leads to the emergence of an in-plane electric field for low energy carriers, which is related to their real space Berry curvature -- the moir\'e magnetic field -- through the Faraday's law of induction. These emergent electromagnetic fields, having opposite signs at the time reversal pair of valleys, can be exploited to manipulate valley and spin in the moir\'e landscape under the control by a bias pulse or a terahertz irradiation.