High field vortex matching effects in superconducting Nb thin films with a nanometer-sized square array of antidots

Nb thin films containing a regular square array of antidots with 17 nm diameter and 50 nm spacing have been fabricated using a relatively simple lithographic process. The critical current density jcH curves, obtained here by electric transport measurements, exhibit commensurability effects with pronounced maxima just above the expected 0H1=0.830 T and 0H1/2=0.415 T matching fields, down to temperatures as low as 2.3 K. The behavior of jcH as well as the position of the maxima are consistent with the ones calculated in the framework of the time dependent Ginzburg- Landau model. © 2010 American Institute of Physics.