Millisecond dynamics of thermal expansion of mechanically controllable break junction electrodes studied in the tunneling regime

The thermal expansion dynamics of W, Pt-Ir, and Au mechanically controllable break junction electrodes was studied in the millisecond range. By measuring a transient tunnel current as a function of time, we found that, at low temperatures, the electrode elongation Deltas similar tot(1/2) due to the large values of thermal diffusivity of metals. The magnitude of Deltas varies in direct proportion to the power P dissipated in the electrodes. (C) 2001 American Institute of Physics.