Spin-Pumping-Induced Inverse Spin Hall Effect in Nb/Ni80Fe20 Bilayers and its Strong Decay Across the Superconducting Transition Temperature
Spin-Pumping-Induced Inverse Spin Hall Effect in Nb/Ni80Fe20 Bilayers and its Strong Decay Across the Superconducting Transition Temperature
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DOI：
10.1103/physrevapplied.10.014029
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发表时间：
2018-07-27
影响因子：
4.6
通讯作者：
Blamire, Mark G.
中科院分区：
文献类型：
--
作者：
Jeon, Kun-Rok;Ciccarelli, Chiara;Blamire, Mark G.
我们在铁磁共振下测量了Nb/Ni80Fe20双层膜的自旋霍尔效应(ISHE)，量化了Nb的自旋霍尔角(SH)和自旋扩散长度L(SD)。通过改变Nb的厚度Tm，并与Ni80Fe20/Pt参比样品相比较，估算出Nb的室温(SH)和L(SD)值分别约为-0.001和30 nm。对于不同的t(Nb)，我们还研究了ISHE随温度T的变化。在Nb的超导转变温度T-c以上，观察到了ISHE明显的与t(Nb)相关的T演化，而在T-c以下，ISHE电压迅速下降，并且低于我们的测量装置在较低T下的灵敏度。这表明准粒子(QP)电荷不平衡弛豫长度在T-c上的强烈衰减，这得到了对不同样品几何形状的ISHE的额外研究和模型计算的支持。我们的发现表明，在开发打算利用QP介导的自旋到电荷相互转化的超导体自旋霍尔器件时，应该仔细考虑。
We quantify the spin Hall angle theta(SH) and spin-diffusion length l(sd) of Nb from inverse spin Hall effect (ISHE) measurements in Nb/Ni80Fe20 bilayers under ferromagnetic resonance. By varying the Nb thickness tom, and comparing to a Ni80Fe20/Pt reference sample, room temperature values of theta(SH) and l(sd) for Nb are estimated to be approximately -0.001 and 30 nm, respectively. We also investigate the ISHE as a function of temperature T for different t(Nb). Above the superconducting transition temperature T-c of Nb, a clear t(Nb)-dependent T evolution of the ISHE is observed whereas below T-c, the ISHE voltage drops rapidly and is below the sensitivity of our measurement setup at a lower T. This suggests the strong decay of the quasiparticle (QP) charge-imbalance relaxation length across T-c, as supported by an additional investigation of the ISHE in a different sample geometry along with model calculation. Our finding suggests careful consideration should be made when developing superconductor spin Hall devices that intend to utilize QP-mediated spin-to-charge interconversion.