Photoinduced Metal-to-Insulator Transitions in 2D Moir\'e Devices

TL;DR

This paper demonstrates an ultrafast photoinduced transition from metallic to insulating states in 2D moiré heterostructures, revealing a new method for controlling correlated electronic phases far from equilibrium.

Contribution

It reports the first observation of a reverse photoinduced metal-to-insulator transition in 2D moiré devices, using photo-thermionic hole injection to achieve metastable insulating states.

Findings

Metastable insulators with microsecond lifetimes were created.

Ultrafast control of electronic phases was achieved in van der Waals heterostructures.

Photo-thermionic hole injection enables reversible phase transitions.

Abstract

Photoexcitation has been utilized to control quantum matter and to uncover metastable phases far from equilibrium. Among demonstrations to date, the most common is the photo-induced transition from correlated insulators to metallic states; however, the reverse process without initial orders has not been observed. Here, we show ultrafast metal-to-insulator transition in gate-doped WS2/WSe2 and WSe2/WSe2 moir\'e devices using photo-thermionic hole injection from graphite gates. The resulting correlated insulators are metastable, with lifetimes exceeding microseconds. These findings establish an effective mechanism for the ultrafast control of correlated electronic phases in van der Waals heterostructures.