Proximity effect in the superconducting magnetization of a Pb/Cu bilayer film with an antidot lattice

• Published in: Physica. C, Superconductivity Superconductivity, 2003-08, Vol.391 (2), p.196-202
• Main Authors: Metlushko, V.V., DeLong, L.E., Moshchalkov, V.V., Bruynseraede, Y.
• Format: Article
• Language: English
• Subjects: Antidot arrays; Flux pinning; Proximity effect; Superconducting thin films
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/S0921-4534(03)00897-9

AC magnetization measurements are reported for a superconducting Pb (500 Å)/Cu (100 Å) film bilayer with a triangular lattice of antidots of diameter D=0.35 μm and spacing d=1.0 μm. Sharply peaked magnetization anomalies occur at applied DC magnetic fields H n = nH 1, where 1⩽ n⩽3, and H 1=24 Oe is the first “matching field” at which every antidot traps exactly one fundamental flux quantum Φ 0. The peaked nature of the matching anomalies is similar to the behavior of Josephson networks (having d/ D≈1), but differs from more step-like structures observed in the magnetization of other patterned films with d/ D≫1. The n=3, 4 matching anomalies successively disappear when the applied field is tilted away from the bilayer normal by 70–84°. 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.