Commensurability effects in magnetic properties of superconducting thin films with periodic submicrometric antidots,

V. BEKERIS, C. CHILIOTTE, D. PÉREZ DAROCA, G. PASQUINI, J. VILLEGAS

Buenos Aires, Argentina

Congreso; Fronteers on Condensed Matter; 2008

CAC-CNEA

Elastic media interacting with a periodic pinning potential represents the behavior of a number of dierent physical systems, as for example charge and spin density waves, adsorbed atomic layers in periodic substrates, and vortex lattice (VL) in type II superconductors with arti cial periodic pinning centers. One of the main features that results in the case of VLs is the presence of commensurate or matching field effects, where pinning or critical current seems to increase, but the mechanism remains still an open question. In this work we examine the response of superconducting vortices interacting with a regular array of sub micrometric "antidots" or holes and with non periodic weak pinning centers. ac and dc magnetic properties in Nb thin lms ( 100 nm thick), deposited on porous anodized aluminum oxide (AAO) substrates with pores 40 nm in diameter, self-assembled in triangular array with mean distance 100 nm, are compared with  hose obtained for a reference Nb continuous lm. Origin and nature of commensurability or matching field effects, observed both in ac and dc experiments for the sample with antidots, is discussed within the picture of single/multiquanta pinned fux, interstitialvortex pinning and Little and Parks TC suppression effects.