Infinite Magnetoresistance from the Spin Dependent Proximity Effect in Symmetry Drivenbcc−Fe/V/FeHeteroepitaxial Superconducting Spin Valves

Abstract

Superconductivity in fully epitaxial bcc-Fe/V/Fe hybrid spin valve structures is influenced by the spin currents and supercurrents as well as band symmetry. The transition temperature is spin dependent in the presence of the proximity effect. A unique feature in this system is the band symmetry filtering taking place at the Fe/V interface. The absence of Delta2 Bloch states at the Fermi level in the Fe spin majority channel leads to spin selectivity and reduced transparency at the interface. Infinite magnetoresistance with clear remanence states is obtained, and implies the potential for spintronic applications.

Superconducting spin-valve effect and triplet superconductivity inCoOx/Fe1/Cu/Fe2/Cu/Pbmultilayer

“…A large number of works confirmed the predicted influence of the mutual orientation of the magnetizations in the F1/S/F2 structure on T c (see, e.g., [16][17][18][19][20][21]). However, the magnitude of the spin valve effect ∆T c = T AP c − T P c turns out to be smaller than the width of the superconducting transition δT c itself.…”

Origin of the Inverse Spin Switch Effect in Superconducting Spin Valves

“…However, opposite signs of this effect were observed in different spin valve systems. Several groups found a higher spin valve resistance in the parallel (P) state of the two F layers than in the antiparallel (AP) state (R P > R AP ) [11,12,13,14,15]. Known as the standard SSE, this phenomenon arises from Cooper pair breaking by the exchange fields of the F layers.…”

“…It is well established that the resistance of F/S/F spin valves near T c depends on the state of magnetization of the F layers [11,12,13,14,15,16,17,18,19,20]. However, opposite signs of this effect were observed in different spin valve systems.…”

Ferromagnetic proximity effect ina-CoxSi1−x/Nbbilayers: Role of magnetic disorder and interface transparency

“…5,30 This reflects the increase in the ferromagnetic coherence length F as magnetic order becomes weaker. However, the behavior of S/F hybrids is often much more complex: for example, an enhanced superconducting transition was observed in Nb/Fe/Cu multilayers when the Curie temperature of the Fe layer increased from 250 to 1000 K as a result of a fcc-bcc structural transition 31 and, in V / Fe x V 1−x multilayers, the proximity effect presents a nonmonotonous dependence on iron content 23 that has been attributed to changes in interface transparency due to band mismatch at the V/Fe interface 14 as a result of exchange splitting in the ferromagnet.…”

“…1 The study of hybrid structures, such as superconducting/magnetic multilayers, [2][3][4][5][6][7][8] superconducting/ magnetic/superconducting junctions, 9 or superconducting magnetic nanostructures, 10 has revealed many remarkable phenomena such as direct and inverse proximity effect, 11 reentrant superconductivity 12 and critical temperature oscillations, or infinite magnetoresistance in superconducting spin valves. 13,14 Active theoretical work [15][16][17][18][19][20][21][22] in this field is helping to disentangle the subtle interplay between superconductivity and magnetism, depending on the different structural parameters of the superconducting/ferromagnetic ͑F͒ materials and the oscillating behavior of the superconducting order parameter within the ferromagnetic layers.…”