Out-of-Plane Oscillating Electric Fields Unlock Low-Temperature Nonequilibrium Superionicity in Quasi-Two-Dimensional AgCrSe2

Abstract Superionic conductors enable exceptionally fast ion transport and offer broad technological potential, but their highly conductive states are typically accessible only above the mobile-ion sublattice order–disorder transition temperature. Here, electric-field-responsive machine-learning molecular dynamics reveals a nonequilibrium route to superionic transport in quasi-two-dimensional AgCrSe2 under an out-of-plane oscillating electric field. At 300 K, far below the transition temperature near 475 K, the field activates fast in-plane Ag+ transport with an ionic conductivity reaching ∼1.7 S cm−1. This originates from field-driven dynamic disorder of Ag+ across two equivalent sub-lattices. The highly conductive, dynamically disordered state emerges when the driving half-period approaches the characteristic Ag-sublattice switching time, which shortens with increasing temperature and field amplitude. At strong fields, this timescale is consistent with field-assisted thermal activation, while weak-field deviations suggest additional dynamics. These results show timescale-matched periodic driving as a route to low-temperature nonequilibrium superionic transport.