(a) FE-SEM images of a portion of the nanoporous Nb film. A sketch (not on scale) of the sample geometry is shown in the inset. (b) Zooming-in on individual pores with indication of interpore distance and pore diameter. In the inset we show the Fourier transform determined on a area of the image in (a).
(a) Magnetic field dependence of the critical current density for the Nb film with antidots (S1, solid circles) and for the reference sample (S0, open circles) at two temperatures corresponding to same reduced temperature . In the inset are shown the curves of both samples. (b) Critical current density vs the magnetic field measured at four different temperatures for the Nb film with antidots. Thick (dashed) vertical lines indicate integer (rational) theoretically expected matching fields.
(a) Gray scale plot of the function used into TDGLE to model a square array of antidots. A profile of as a function of at centerline of an antidot column is also shown. (b) Normalized critical current vs the applied magnetic field calculated for the strip with antidots (open symbols) and for the strip with no antidots (solid line). Dashed vertical lines indicate integer and rational theoretically expected matching fields.
(a) Calculated loop of the strip with antidots. Dashed vertical lines indicate integer and rational theoretically expected matching fields. The two inset show contour plots of the squared order parameter at and where we have, respectively, half and full vortex filling of pinning centers. (b) (solid line) is compared with critical current curve (open circles) at same temperature. Thicker lines in the show magnetic field ranges where stable half and full vortex filling are achieved.
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