Acoustic waveguide modes observed in electrically heated metal wires

The steady-state resistance of small metal wires subject to an electric field is found to exhibit periodic resonances that scale with the width of the wire. The energies of the resonances have been determined using the low-temperature corrections to the resistance of the wires, and are shown to correspond to acoustic modes of the wire. We conclude that the resonances originate from increased energy relaxation that occurs when the electron system gains enough energy from the electric field to emit phonons in a higher acoustic subband of the wire.