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arXiv 2103.13368cond-mat.supr-con
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超导自旋阀中超导体邻近效应与准粒子自旋衰变竞争的证据

Evidence for competition between the superconductor proximity effect and quasiparticle spin-decay in superconducting spin-valves

B. Stoddart-Stones, X. Montiel, M. G. Blamire, J. W. A. Robinson

摘要:

铁磁体(F)中上自旋电子和下自旋电子的态密度的差异导致铁磁体/铁磁体(F/N)界面处的电子的自旋相关散射。在F/N/F自旋阀中,这导致反平行(AP)和平行(P)磁化状态之间的电阻($ΔR$)的电流无关的差异。巨磁电阻(GMR),$ΔR = R(AP) - R(P)$,是积极的,由于在AP状态的多数和少数自旋电子的散射增加。如果用N代替超导体(S),则GMR和超导自旋阀效应之间存在竞争:在AP态,作用在S上的净磁交换场降低,超导性增强,这意味着$R(AP)$降低。对于电流垂直于平面(CPP)自旋阀,现有的实验研究表明巨磁电阻效应($ΔR>0$)优于超导自旋阀效应($ΔR<0$)[J. Y. Gu等人,B 66,140507(R)(2002)]。然而,在这里,我们报告的交叉从GMR($ΔR > 0$)的超导自旋阀效应($ΔR < 0$)在CPP F/S/F自旋阀的超导体厚度降低到临界值以下。

英文摘要:

The difference in the density of states for up- and down-spin electrons in a ferromagnet (F) results in spin-dependent scattering of electrons at a ferromagnet / nonmagnetic (F/N) interface. In a F/N/F spin-valve, this causes a current-independent difference in resistance ($ΔR$) between antiparallel (AP) and parallel (P) magnetization states. Giant magnetoresistance (GMR), $ΔR = R(AP) - R(P)$, is positive due to increased scattering of majority and minority spin-electrons in the AP-state. If N is substituted for a superconductor (S), there exists a competition between GMR and the superconducting spin-valve effect: in the AP-state the net magnetic exchange field acting on S is lowered and the superconductivity is reinforced meaning $R(AP)$ decreases. For current-perpendicular-to-plane (CPP) spin-valves, existing experimental studies show that GMR dominates ($ΔR>0$) over the superconducting spin valve effect ($ΔR<0$) [J. Y. Gu et al., Phys. Rev. B 66, 140507(R) (2002)]. Here, however, we report a crossover from GMR ($ΔR > 0$) to the superconducting spin valve effect ($ΔR < 0$) in CPP F/S/F spin-valves as the superconductor thickness decreases below a critical value.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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