Low Temperature Laboratory, Physics Department, IIT, Madras, 600 036, India
Abstract:
Tunneling measurements were performed at 4.2 K on well-characterized NdBa2Cu3O7?y samples using a sandwich configuration with an artificially grown barrier layer (sputtered indium oxide) and Pb0.5In0.5 counter electrode. The conductance spectra exhibited well-defined structures characteristic of gap opening. Fitting the data to a life-time broadened BCS density of states function yielded the following values: 20 meV for the energy gap Δ, 1.5 meV for the line width Γ and 5.3 for 2Δ/kBTc.