Tunable Spatiotemporal Orders in Driven Insulators

We show that driving optical phonons above a threshold fluence induces spatiotemporal orders, where material properties oscillate at an incommensurate wave vector q_{0} in space and at half the drive frequency in time. The order is robust against temperature on timescales much larger than the lifetime of the excited modes and can be accompanied by a static 2q_{0} modulation. We make predictions for time-resolved diffraction and provide estimates for candidate materials. Our results show the possibility of using THz waves in solids to realize tunable incommensurate orders on the nanoscale.