Figure 1
From: Probing dynamics and pinning of single vortices in superconductors at nanometer scales
Magnetic imaging of a single vortex.
(a), Scanning SQUID-on-tip image of Bdc(x,y) showing a single vortex (bright) in a thin Pb film patterned into an 8 µm wide microbridge at T = 4.2 K. The microbridge is in the Meissner state (dark) and the enhanced field outside the edges (bright) is due to the screening of the applied field of 0.3 mT. (b), Scanning image of Bac(x,y) acquired simultaneously with (a) showing the vortex response to an ac current of Iac = 0.94 mA peak-to-peak (ptp) at 13.3 kHz applied to the microbridge. The Meissner response is visible along the microbridge (Bac = 0, light brown) with positive (negative) Bac outside the left (right) edge due to the field self-induced by Iac. (c), A zoomed-in image of the measured Bdc(x,y) of a vortex. (d–f), Numerically derived ∂Bdc/∂x, ∂Bdc/∂y and −xac∂Bdc/∂x−yac ∂Bdc/∂y with xac = 1.6 nm and yac = −1.9 nm values obtained by a fit to (g). (g), Experimentally measured Bac(x,y) of the vortex driven by Iac acquired simultaneously with (c).
