We have taken magnetic-field images in a wide temperature range of 4–90 K for square-shaped NdBa2Cu3Oy (Tc=89–92 K) thin-film patterns with an array of slots and a linewidth of 4–40 μm by using a scanning superconducting quantum interference device microscope. The thin-film patterns were cooled below 10 K in a various ambient magnetic field of 0.5–100 μT to investigate the behavior of flux trapping. The number of trapped flux quanta clearly decreases with decreasing the ambient field and the linewidth, and flux quanta are completely excluded from the patterns below the threshold-field strength, which agrees well with the Clem’s criterion [E. Dantsker, S. Tanaka, and J. Clarke, Appl. Phys. Lett. 70, 2037 (1997)]. Moreover, additional flux trapping in the pattern-edge regions is observed by applying a field above 50 μT at temperatures near 77 K.

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