  We report on ultrafast optical experiments in which femtosecond mid-infrared
radiation is used to excite the lattice of complex oxide heterostructures. By
tuning the excitation energy to a vibrational mode of the substrate, a
long-lived five-order-of-magnitude increase of the electrical conductivity of
NdNiO3 epitaxial thin films is observed as a structural distortion propagates
across the interface. Vibrational excitation, extended here to a wide class of
heterostructures and interfaces, may be conducive to new strategies for
electronic phase control at THz repetition rates.
