Anomalous proximity effect in spin-valve superconductor/ferromagnetic metal/ferromagnetic metal structures

Karminskaya, T. Yu.; Golubov, A. A.; Kupriyanov, M. Yu.

doi:10.1103/physrevb.84.064531

Cited by 25 publications

(24 citation statements)

References 51 publications

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“…This is in agreement with previous 35,38,40,41,[55][56][57] experimental and theoretical results. Due to the non-monotonicity of |f 1,avg | with h [see Fig.…”

Section: Triplet and Singlet Pair Correlationssupporting

confidence: 83%

“…We again consider a broad range of exchange field strengths, as shown in the legend. One of the more obvious features is that the maximum of |f 1,avg | typically does not occur for orthogonal relative exchange fields, 38 for smaller β 1 90…”

Section: Triplet and Singlet Pair Correlationsmentioning

confidence: 99%

“…The damped oscillatory behavior of the pair correlations can lead to spectroscopic signatures in the form of DOS inversions, 58 and multiple oscillations. 24 In the quasiclassical approximation, 35,38,55,56 a ZEP can emerge from the long-range triplet correlations 33,59 in SF F systems. However, this approximation is not appropriate for experimental conditions involving strong magnets and clean interfaces.…”

Section: Local Density Of Statesmentioning

confidence: 99%

“…Nearly all of the past theoretical works on SF F structures have considered the diffusive case, [34][35][36][37][38] where impurities strongly scatter the quasiparticles. The clean regime has been studied, using a self-consistent solution of the Bogoliubovde Gennes (BdG) 39 equations, in Ref.…”

Section: Introductionmentioning

confidence: 99%

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Zero-energy peak and triplet correlations in nanoscale superconductor/ferromagnet/ferromagnet spin valves

2015

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Using a self-consistent Bogoliubov-de Gennes approach, we theoretically study the proximity-induced density of states (DOS) in clean SF F spin-valves with noncollinear exchange fields. Our results clearly demonstrate a direct correlation between the presence of a zero energy peak (ZEP) in the DOS spectrum and the persistence of spin-1 triplet pair correlations. By systematically varying the geometrical and material parameters governing the spin-valve, we point out to experimentally optimal system configurations where the ZEPs are most pronounced, and which can be effectively probed via scanning tunneling microscopy. We complement these findings in the ballistic regime by employing the Usadel formalism in the full proximity limit to investigate their diffusive SF F counterparts. We determine the optimal normalized ferromagnetic layer thicknesses which result in the largest ZEPs. Our results can serve as guidelines in designing samples for future experiments.

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“…This is in agreement with previous 35,38,40,41,[55][56][57] experimental and theoretical results. Due to the non-monotonicity of |f 1,avg | with h [see Fig.…”

Section: Triplet and Singlet Pair Correlationssupporting

confidence: 83%

Section: Triplet and Singlet Pair Correlationsmentioning

confidence: 99%

Section: Local Density Of Statesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Zero-energy peak and triplet correlations in nanoscale superconductor/ferromagnet/ferromagnet spin valves

2015

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“…45.+c,74.78.Fk, In the field of superconducting spintronics, there is interest in spin-controlled proximity effects for manipulating the superconductivity in ferromagnet (F ) and superconductor (S) layered systems [1,2]. When an S layer is in contact with two ferromagnets, creating a superconducting spin valve, the superconducting state can be controlled by changing the relative magnetization directions [3][4][5]. The basic superconducting spin-valve involves SF F structures [3,6] where switching between relative parallel and antiparallel magnetizations modifies the oscillatory singlet pairing in the F regions.…”

mentioning

confidence: 99%

Half-metallic superconducting triplet spin valve

Halterman

Alidoust

2016

Phys. Rev. B

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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.

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