Altering the Superconductor Transition Temperature by Domain-Wall Arrangements in Hybrid Ferromagnet-Superconductor Structures

Abstract

The [Co/Pt]n/Nb/[Co/Pt]n hybrids with perpendicular magnetic anisotropy reveal enhanced superconductivity with the presence, and the arrangements, of domain walls, where superconductivity persists. An in-plane field can manipulate the domain walls from labyrinth to stripe patterns and drive the hybrids from normal to superconducting. We observe anisotropic superconductivity in hybrids with stripe domains, along which enhanced superconductivity is realized.

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

“…Previously, similar experiments in which a low-T C S (Nb) was used were interpreted in terms of T C variations caused by Cooper-pair breaking, and stray magnetic field effects were dismissed. 23 However, our combination of magnetic force microscopy (MFM), anomalous Hall effect (AHE) 29 measurements, current dependent magneto-transport measurements, and magnetostatic calculations allows us to unambiguously connect the resistance switching observed here to vortex dynamic effects induced by the stray fields. Notably, we can correlate the magnetic history-dependent pinning of vortices [30][31][32] with the varying F domain structure.…”

“…[14][15][16][17][18][19][20][21][22][23][24] This effect has been explained in terms of various mechanisms that produce a shift of the critical temperature T C depending upon the configuration of the F layers: Cooper-pair breaking either (i) due to the exchange field induced in the S 14,16,22,23,25 or (ii) due to the accumulation of spin-polarized quasiparticles 15,17,20,26 and (iii) Cooper-pair formation due to crossed Andreev reflection. 27 On the other hand, various low-T C S/F systems show resistance switching effects produced by stray magnetic fields generated by the F layers' domain structure.…”

Domain-wall-induced magnetoresistance in pseudo-spin-valve/superconductor hybrid structures

“…Magnetic non-uniformities adjacent to a superconductor may therefore lead to the enhancement or reduction of the superconducting condensation energy. [5][6][7][8] Among other factors the observation of one or the other behavior depends on the magnetic configuration, [6][7][8] on the size of domains relative to the superconducting coherence length, 9 and on the kind of DW present in a ferromagnet. 10 Recent experiments have been devoted to study the influence of DW-generated magnetic stray fields onto superconductivity.…”

“…10 Recent experiments have been devoted to study the influence of DW-generated magnetic stray fields onto superconductivity. Those include thin-film, in-plane, 11,12 and out-of-plane 9 magnetized, hybrid SC-FM structures, as well as patterned SC-FM nanostructures. 13,14 Several recent investigations of SC-FM hybrid systems studied the interaction of superconductivity with relatively weak ferromagnets such as CuNi-alloys, 15,16 and few works were focused on the interplay of superconductivity and stray magnetic fields originating from strong ferromagnetic materials such as Py (Ni 80 Fe 20 ), Co, and Fe.…”

Suppression of superconductivity in Nb by IrMn in IrMn/Nb bilayers

“…Antiferromagnet/ferromagnet (AFM/FM) 1,2 and ferromagnet/superconductor (FM/S) [3][4][5][6][7] heterointerfaces have been investigated intensively in the last few decades due to their importance in both fundamental physics studies and device applications. Compared to the AFM/FM and FM/S interfaces, however, the amount of work on antiferromagnet/superconductor (AFM/S) heterointerfaces is quite limited.…”