Monday, July 1, 2013

1306.6639 (Ruoyu Chen et al.)

Electron heating in atomic-scale Au break junctions    [PDF]

Ruoyu Chen, Patrick J. Wheeler, M. Di Ventra, D. Natelson
Heating in nanoscale systems driven out of equilibrium is of fundamental importance, has ramifications for technological applications, and is a challenge to characterize experimentally. Prior experiments using nanoscale junctions have largely focused on heating of vibrational degrees of freedom, while heating of the electrons has been mostly neglected. We report measurements in atomic-scale Au break junctions, in which the bias-driven component of the current noise is used as a probe of the effective electronic temperature. At low biases ($<$ 150 mV) the noise is consistent with expectations of shot noise at a fixed electronic temperature. At higher biases, a nonlinear dependence of the noise power is observed consistent with a bias-driven increase in the effective electronic temperature, independent of the conductance of the junction. This result is inconsistent with a possible confounding effect of flicker noise. We discuss the implications of these observations for other nanoscale systems.
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