Magnetic pinning of vortices in a superconducting film: The (anti)vortex-magnetic dipole interaction energy in the London approximation

Abstract

The interaction between a superconducting vortex or antivortex in a superconducting film and a magnetic dipole with in-or out-of-plane magnetization is investigated within the London approximation. The dependence of the interaction energy on the dipole-vortex distance and the film thickness is studied and analytical results are obtained in limiting cases. We show how the short range interaction with the magnetic dipole makes the co-existence of vortices and antivortices possible. Different configurations with vortices and antivortices are investigated. 74.60.Ge, 74.25.Dw, 74.25.Ha

Vortex states in high-Tc superconductors and superconductivity in modern nano-science and engineering

“…Since, this boundary condition gives strongest restriction to the vortices, the triangular lattice is distorted to accommodate them with the shape of the sample at the minimum cost of the free energy. This re-organization phenomenon is observed experimentally, and it is in good accordance with the recent theoretical calculations [6,7,[71][72][73][74][75][76][77][78][79][80][81][82] In square and triangle samples with the sides of 10 and 30 mm similar behaviors have been observed. A typical and beautiful example of the image of the multivortex state for the purpose of display is shown in Fig.…”

Superconducting properties of perforated NbN films using ordered arrays of ferromagnetic nanowires

“…The stray magnetic fields of the magnetic dots were acting as pinning centers for the vortices. Since then, many experimental [7][8][9][10][11][12][13][14][15][16][17] and theoretical [18][19][20][21] works have been performed. Notably, Hoffmann et al 8 compared experimentally the vortex pinning in superconducting films deposited on top of square arrays of magnetic and nonmagnetic dots of different sizes.…”

“…The shift of the corresponding phase diagram T c (H ) takes its origin in the creation of vortexantivortex pairs (V-AV) in the superconductor due to the stray field of the dots. 19 Gillijns et al 9,10 tuned this field-induced superconductivity by modifying the magnetic state of the ferromagnetic dots. They were able to modify the number of V-AV pairs generated by each dot and, therefore, to shift at will (by discrete steps) the phase diagram up to a maximum value.…”

Quantitative magneto-optical investigation of superconductor/ferromagnet hybrid structures

“…Vortices generated in a superconductor by an external magnetic field experience magnetic pinning by a domain structure due to interactions of the stray fields of the magnetic structure with screening currents in the superconductor [61][62][63][64][65][66]. Moreover, the magnetic pattern is expected to spontaneously induce vortices in the superconductor even in zero applied field, with vortices of opposite polarity occupying the alternate sets of squares [63,66,67].…”