Electrical Conduction in Ensembles of Tunneling-Coupled Fine Particles of Tin. II. Fluctuations of the Josephson Current

The zero-bias resistance has been measured on ensembles of tunneling-coupled fine particles of Sn with the average diameter ranging 1250–2700 A over the temperature region of 1.5–4.2 K. In these ensembles, the interparticle coupling can be varied independently of the particle size. As the interparticle coupling becomes weak, the resistive transition temperature, T 0 , becomes sizably lower than T c of the particles. The behavior of the resistance above T 0 is explained by the fluctuations of the Josephson current by use of a correction parameter for the electrical capacitance between particles. The shift of T 0 is inversely proportional to the coupling energy between particles. As the particle size decreases, the charging energy of a particle seems to bring about lowering of T 0 .