Electron tunneling measurements of the high T sub c superconductor Y sub 1 Ba sub 2 Cu sub 3 O sub (9-delta).

Current-voltage tunneling characteristics in the high critical temperature superconducting material Y sub 1 Ba sub 2 Cu sub 3 O sub (9-delta) have been measured using the break junction technique. Sharp gap structure was observed with the largest superconductive energy gap DELTA measured to be 19 meV to 20 meV. Using the observed critical temperature of 93K (mid-point of the resistive transition), this energy gap corresponds to 2delta/k sub B T sub c = 4.8 at T = 4 K.