Periodic arrays of pinning centers in thin vanadium films

摘要

Commensurability effects between the superconducting flux line lattice and a211u001esquare lattice (period d=1(micro)m and diameter D=0.4(micro)m) of submicron holes 211u001ein 1500 (angstrom) vanadium films were studied by atomic force microscopy, DC 211u001emagnetization, AC susceptibility, magnetoresistivity and I-V measurements. Peaks 211u001ein the magnetization and critical current at matching fields are found to depend 211u001enonlinearly upon the value of external AC field or current, as well as the 211u001einferred symmetry of the flux line lattice.