Corbino experimental set-up for Cooper pair mass spectroscopy and determination of mobility in normal phase

Abstract

We are suggesting an electronic method for Cooper pair mass spectroscopy of thin superconducting films. The method can be applied, for example, for 100 nm thin high-T_c films grown on insulator substrate 10 mm X 10 mm. In Corbino geometry two Ohmic contacts have to be made on the film evaporating Ag or using silver paste: one circle with radius r_a (1) and a ring electrode with internal radius r_b (2). In the in-between space (r_a,r_b) a ring electrode from mylar assures a capacitive connection between the superconducting layer and the metallized surface (3) of the mylar. In such a way we have an field effect transistor (FET) type structure with a circular gate. When at low enough temperatures T << T_c an AC current with frequency omega is applied between the circle source (1) and the ring-shaped drain (2) an AC Bernoulli voltage with double frequency 2f appears between the gate (3) and the source (1). The 2f signal depends on Cooper pair effective mass and its systematic investigation gives a Cooper pair mass spectroscopy. In the normal phase 2f gives logarithmic derivative of the density of states (DOS) with respect of Fermi energy. Applying a gate voltage in the same structure gives the mobility of the normal phase.