Bistable superlattice switching in a quantum spin Hall insulator

"Bistable switching typically arises from ferroic orders, such as ferroelectricity and ferromagnetism, in which the bistable states are encoded in charge or spin degrees of freedom. Here we report the observation of bistable superlattice switching in monolayer TaIrTe4, a dual quantum spin Hall insulator, where switching occurs between two lattice configurations with sharply contrasting periodicities."

"In a pristine monolayer, we observe the spontaneous emergence of a long-period superlattice that can be programmed on and off in a non-volatile manner by electrostatic tuning of low-energy electronic states. This switching toggles the system between two structural configurations with unit cell areas differing by two orders of magnitude."

Bistable switching in monolayer TaIrTe4, a dual quantum spin Hall insulator, occurs between two distinct lattice configurations with sharply contrasting periodicities. A spontaneous long-period superlattice emerges in pristine monolayers and can be programmed on and off non-volatilely through electrostatic tuning of low-energy electronic states. This switching mechanism toggles the system between structural configurations whose unit cell areas differ by two orders of magnitude. The underlying mechanism involves two independent and distinct instabilities that drive the bistable behavior, representing a novel form of structural switching distinct from conventional ferroic order-based bistability.

Read at www.nature.com