Ultrafast spectroscopic probes of acoustic phonons in multiferroic thin films and semiconductor heterostructures

Abstract

The interaction of an ultrashort pulse of light with acoustic phonons provides a convenient and non-contact methodology to determine the elastic properties of nanomaterials. The epitaxial growth of thin films with thicknesses of a few hundred nanometres can create multiferroics with properties tailored by strain engineering. Ultrafast photoacoustic spectroscopy was used to determine the elastic constant and magnon response of the room temperature magnetoelectric bismuth ferrite. When applied to semiconductor quantum well heterostructures photoacoustic spectroscopy provides a precise probe of superlattice periodicity and interface quality.