Nanoscale magnetic Josephson junctions and superconductor/ferromagnet proximity effects for low-power spintronics
Competition between superconducting and ferromagnetic ordering at interfaces between ferromagnets (F) and superconductors (S) gives rise to several proximity effects such as odd-triplet superconductivity and spin-polarized supercurrents. A prominent example of an S/F proximity effect is the spin switch effect observed in S/F/N/F superconducting spin valve multilayers, in which the superconducting transition temperature Tc is controlled by the angle Φ between the magnetic moments of the F layers separated by a nonmagnetic metallic spacer N. We carried out an experimental study of spin switch effect in Nb/Co/Cu/Co/CoOx nanowires measured as a function of bias current flowing in the plane of the layers. These measurements reveal an unexpected dependence of Tc (Φ) on the bias current: Tc (Φ) – Tc (0) changes sign with increasing current bias. We attribute the origin of this bias dependence of the spin switch effect to a spin Hall current originating in Nb and flowing perpendicular to the plane of the multilayer, which suppresses Tc of the multilayer. The bias dependence of spin switch effect can be important for hybrid F/S devices such as cryogenic memory for superconducting computers when device dimensions are scaled down to the nanometer length scale.
- Research Organization:
- Univ. of California, Irvine, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- DOE Contract Number:
- SC0014467
- OSTI ID:
- 1577326
- Report Number(s):
- DOE-UCI-SC0014467; 9498240253
- Country of Publication:
- United States
- Language:
- English
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