Full spin switch effect for the superconducting current in a superconductor/ferromagnet thin film heterostructure

Abstract

Superconductor/ferromagnet (S/F) proximity effect theory predicts that the superconducting critical temperature of the F1/F2/S or F1/S/F2 trilayers for the parallel orientation of the F1 and F2 magnetizations is smaller than for the antiparallel one. This suggests a possibility of a controlled switching between the superconducting and normal states in the S layer. Here, using the spin switch design F1/F2/S theoretically proposed by Oh et al. [Appl. Phys. Lett. 71, 2376], that comprises a ferromagnetic bilayer separated by a non-magnetic metallic spacer layer as a ferromagnetic component, and an ordinary superconductor as the second interface component, we have successfully realized a full spin switch effect for the superconducting current.

Experimental and theoretical analysis of the upper critical field in ferromagnet–superconductor–ferromagnet trilayers

“…Based on the unique properties of S/F hybrids, several kinds of device physics were proposed such as proximity-effect superconducting spin-switching [13,14,15,16,17] and Josephson current switching [18,19,20] actuated by an external magnetic field. Very recently, magnetic-field-controlled superconductivity switching in the S/F proximity systems [21,22,23,24,25] and the Josephson current switching in the S/F/S junctions [26,27] were demonstrated experimentally.…”

Isolation of proximity-induced triplet pairing channel in a superconductor/ferromagnet spin valve

“…The latter construction should be operational upon application of a small external magnetic field. Many experimental works were performed to confirm this effect for the S/F systems with a good contact between metallic F and S layers made of ordinary metals and standard ferromagnets (see, e.g., recent reviews [6]), the full switching between the superconducting and normal states has been realized only in a few cases [7,8] because ∆T c was usually smaller than the width of the superconducting transition δT c .Very recently, Singh et al reported [9] the observation of a colossal triplet spin-valve effect for the S/F1/N/F2 structure made of amorphous MoGe, Ni, Cu, and CrO 2 as the S, F1, N, and F2 layers, respectively. This structure demonstrated variation of T c by ∼ 1 K when changing the relative alignment of the two F layers.…”

“…The latter construction should be operational upon application of a small external magnetic field. Many experimental works were performed to confirm this effect for the S/F systems with a good contact between metallic F and S layers made of ordinary metals and standard ferromagnets (see, e.g., recent reviews [6]), the full switching between the superconducting and normal states has been realized only in a few cases [7,8] because ∆T c was usually smaller than the width of the superconducting transition δT c .…”

“…[5] and ∆T c = 120 mK in Ref. [6]), the full switching between the superconducting and normal states has been realized only in a few cases [7,8] because ∆T c was usually smaller than the width of the superconducting transition δT c .…”

Reentrance phenomenon in superconductor/ferromagnet nanostructures and their application in superconducting spin valves for superconducting electronics

“…Recently, an alternative F1/N/F2/S design of the superconducting spin valve [36] attracted much attention [37][38][39] because of possible high sensitivity of the superconducting T c to generation of the long-range triplet component of superconducting pairing [40,41]. Indeed, recent calculations have shown [42] that not only the "direct switching" ( ) [42], which can be most spectacularly detected as a reentrant behavior of superconductivity as a function of the angle between magnetic moments of the F1 and F2 ferromagnetic layers.…”