Enhancement and Inhibition of Coherent Phonon Emission of a Ni Film in a BaTiO3/SrTiO3 Cavity

We report pump-probe time resolved reflectivity experiments in a hybrid air-Ni metal-BaTiO3/SrTiO3 oxide mirror phonon cavity. We demonstrate that the generated coherent acoustic phonon spectra of the impulsively excited metallic film can be inhibited or enhanced in the phonon cavity with respect to a Ni film directly grown on a SrTiO3 substrate. The experiments are compared with simulations that highlight the role of the phonon density of states in the coherent acoustic emission, extending concepts at the base of the optical Purcell effect to the field of phononics.