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 Δs∼t1/2 due to the large values of thermal diffusivity of metals. The magnitude of Δs varies in direct proportion to the power P dissipated in the electrodes.