title: Influence of phonon dimensionality on electron energy relaxation.
abstract: We studied experimentally the role of phonon dimensionality on electron-phonon (e-p) interaction in thin copper wires evaporated either on suspended silicon nitride membranes or on bulk substrates, at sub-Kelvin temperatures. The power emitted from electrons to phonons was measured using sensitive normal metal-insulator-superconductor tunnel junction thermometers. Membrane thicknesses ranging from 30 to 750 nm were used to clearly see the onset of the effects of two-dimensional (2D) phonon system. We observed for the first time that a 2D phonon spectrum clearly changes the temperature dependence and strength of the e-p scattering rate, with the interaction becoming stronger at the lowest temperatures below approximately 0.5 K for the 30 nm membranes.
authors.affiliation: Nanoscience Center, Department of Physics, FIN-40014, University of Jyväskylä, Finland.
authors.forename: J T
authors.initials: JT
authors.lastname: Karvonen
authors.forename: I J
authors.initials: IJ
authors.lastname: Maasilta