MEASUREMENT OF THE ACOUSTIC-PHONON MEAN FREE-PATH IN A FREESTANDING METAL-FILM

In this paper we describe an electron heating experiment performed on thin free-standing metallic films in a vacuum. In the steady state, the resistance change with electric field is found to be different to that observed on similar films supported by a substrate. By considering the power balance between the electrons and phonons in the film, we show that the phonon mean free path is close to the film thickness and that the electron-phonon coupling strength is consistent with other measurements.