Half-metallic superconducting triplet spin valve

Abstract

We theoretically study a finite size SF1N F2 spin valve, where a normal metal (N ) insert separates a thin standard ferromagnet (F1) and a thick half-metallic ferromagnet (F2). For sufficiently thin superconductor (S) widths close to the coherence length ξ0, we find that changes to the relative magnetization orientations in the ferromagnets can result in substantial variations in the transition temperature Tc, consistent with experiment [Singh et al., Phys. Rev. X 5, 021019 (2015)]. Our results demonstrate that, in good agreement with the experiment, the variations are largest in the case where F2 is in a half-metallic phase and thus supports only one spin direction. To pinpoint the origins of this strong spin-valve effect, both the equal-spin f1 and opposite-spin f0 triplet correlations are calculated using a self-consistent microscopic technique. We find that when the magnetization in F1 is tilted slightly out-of-plane, the f1 component can be the dominant triplet component in the superconductor. The coupling between the two ferromagnets is discussed in terms of the underlying spin currents present in the system. We go further and show that the zero energy peaks of the local density of states probed on the S side of the valve can be another signature of the presence of superconducting triplet correlations. Our findings reveal that for sufficiently thin S layers, the zero energy peak at the S side can be larger than its counterpart in the F2 side.

Spin transport and Spin Tunnelling Magneto-Resistance (STMR) of F|NCSC|F spin valve

“…With the further rotation of θ m the spin current reverses its polarization and becomes maximum for the orthogonal configuration as seen from the Fig.10(a). A similar behaviour is also observed earlier in Ref [112][113][114][115]. If θ m is rotated further to 0.7π the spin current decreases.…”

“…To understand feasibility of ferromangetism and superconductivity, and also the role of magnetization in F|S hybrids, many superconducting spintronic SVs had been extensively studied theoretically [76][77][78][79][80][81][82][83][84][85][86] and experimentally [87][88][89][90][91][92][93][94][95][96]. Previous works on F|S heterostructure and superconducting SVs strongly indicates that the superconducting critical temperature is dependent on the orientation of magnetization.…”

Evolution of pair correlation symmetries and supercurrent reversal in tilted Weyl semimetals

“…In this case, the superconducting gap function should be solved self-consistently to extract T c , which is however, a nontrivial and formidable task that is postponed for future works. 34,35…”

Josephson current through a ferromagnetic bilayer: Beyond the quasiclassical approximation

“…The alternative approach for the analysis of proximity effects in strong ferromagnets is the use of the microscopical approach on the basis of the Bogoliubov-de Gennes (BdG) equations 14 . The exact numerical solutions of these equations may provide additional information to the quasiclassical approach and this method was used in [15][16][17][18][19][20][21][22][23][24] and references cited therein. Recently the interesting experimental results were obtained for the Josephson junctions containing a ferromagnetic spin valve [25][26][27][28][29][30][31] .…”