title: Laserlike vibrational instability in rectifying molecular conductors.
abstract: We study the damping of molecular vibrations due to electron-hole pair excitations in donor-acceptor (D-A) type molecular rectifiers. At finite voltage additional nonequilibrium electron-hole pair excitations involving both electrodes become possible, and contribute to the stimulated emission and absorption of phonons. We point out a generic mechanism for D-A molecules, where the stimulated emission can dominate beyond a certain voltage due to the inverted position of the D and A quantum resonances. This leads to current-driven amplification (negative damping) of the phonons similar to laser action. We investigate the effect in realistic molecular rectifier structures using first-principles calculations.
authors.affiliation: DTU Nanotech, Department of Micro and Nanotechnology, Technical University of Denmark, Ørsteds Plads, Building 345E, DK-2800 Kongens Lyngby, Denmark. jtlu@nanotech.dtu.dk
authors.forename: Jing-Tao
authors.initials: JT
authors.lastname: Lü
authors.forename: Per
authors.initials: P
authors.lastname: Hedegård
authors.forename: Mads
authors.initials: M
authors.lastname: Brandbyge