Hysteretic magnetic pinning and reversible resistance switching in high-temperature superconductor/ferromagnet multilayers

Abstract

We study a high-critical temperature superconducting (YBa 2 Cu 3 O 7-δ )/ferromagnetic (Co/Pt multilayer) hybrid that exhibits resistance switching driven by the magnetic history: depending on the direction of the external field, a pronounced decrease or increase of the mixed-state resistance is observed as magnetization reversal occurs within the Co/Pt multilayer. We demonstrate that stray magnetic fields cause these effects via (i) creation of vortices/antivortices and (ii) magnetostatic pinning of vortices that are induced by the external field.

Tuning vortex confinement by magnetic domains in a superconductor/ferromagnet bilayer

“…A model confining potential may be realized in the planar superconductor(S)/ferromagnet(F) bilayer (SFB), in which the magnetic domains in the F layer create pinning potential for vortices 6,[11][12][13][14][15][16][17][18][19][20] . When the F layer exhibits perpendicular magnetic anisotropy (PMA) with a welldefined direction of the magnetic moment of the domain, the vortices are selectively attracted to the domains of one sign [21][22][23][24][25][26][27][28][29][30][31][32] . Recently, several experiments demonstrated formation of single or multiple vortex chains confined to domains of one sign in SFB's with stripe domain patterns, in which equal amount of +/− domains exist.…”

Enhancement of vortex pinning in superconductor/ferromagnet bilayers via angled demagnetization

“…As previously suggested, the magnetic domains in the F layer create pinning centers for the vortices in the S layer so that tuning the domain structure can result in tuning J c 4,5 . While the principle of magnetic pinning in the SFB's has been extensively discussed theoretically [2][3][4][5][6][7][8][9][10][11] and demonstrated experimentally [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] , the magnitude of the pinning enhancement thus far reported has been modest with a factor of no more than 3, and sometimes even suppression of pinning has been described 18 . Furthermore, it has not been feasible to compare various magnetic pinning results, since the different SFB bilayers used in these studies would render such comparison impractical.…”

Critical current reduction in coated conductors when in-plane fields are applied

“…I, changes in the superconductor critical current, anisotropy, and mixed state resistance depending on the magnetization of the ferromagnet have been reported. [37][38][39][40][41] Song et al have reported that, in parallel field, the hysteretic magnetization curves of the superconducting film included in a coated conductor deposited on a magnetic substrate present features very different from the classical shape obtained with CCs deposited on a nonmagnetic substrate. 22 This confirms that the presence of the ferromagnet has a strong influence on the vortex population in the superconductor.…”