Physica c-superconductivity and its applications vol:391 issue:2 pages:196-202
AC magnetization measurements are reported for a superconducting Ph (500 Angstrom)/Cu (100 Angstrom) film bilayer with a triangular lattice of antidots of diameter D = 0.35 mum and spacing d = 1.0 mum. Sharply peaked magnetization anomalies occur at applied DC magnetic fields H-n = nH(1), where 1 less than or equal to n less than or equal to 3, and H-1 = 24 Oe is the first "matching field" at which every antidot traps exactly one fundamental flux quantum Phi(0). The peaked nature of the matching anomalies is similar to the behavior of Josephson networks (having d/D approximate to 1), but differs from more step-like structures observed in the magnetization of other patterned films with d/D much greater than 1. The n = 3, 4 matching anomalies successively disappear when the applied field is tilted away from the bilayer normal by 70-84degrees. The peaked magnetization, low transition temperature of 6.70 K, reduced angular stability of the flux lattice, and the absence of clear matching anomalies with n > 4, indicate that these properties are novel probes of a proximity effect between normal (Cu) and superconducting (Pb) film layers. (C) 2003 Elsevier B.V. All rights reserved.