Kim K-W, O'Brien L, Crowell P A, Leighton C, Stiles M D
Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Maryland NanoCenter, University of Maryland, College Park, Maryland 20742, USA.
Phys Rev B. 2017 Mar;95(10). doi: 10.1103/PhysRevB.95.104404. Epub 2017 Mar 7.
We theoretically analyze contributions from the Kondo effect to the spin polarization and spin diffusion length in all-metal nonlocal spin valves. Interdiffusion of ferromagnetic atoms into the normal metal layer creates a region in which Kondo physics plays a significant role, giving discrepancies between experiment and existing theory. We start from a simple model and construct a modified spin drift-diffusion equation which clearly demonstrates how the Kondo physics not only suppresses the electrical conductivity but even more strongly reduces the spin diffusion length. We also present an explicit expression for the suppression of spin polarization due to Kondo physics in an illustrative regime. We compare this theory to previous experimental data to extract an estimate of the Elliot-Yafet probability for Kondo spin flip scattering of 0.7 ± 0.4, in good agreement with the value of 2/3 derived in the original theory of Kondo.
我们从理论上分析了近藤效应在全金属非局域自旋阀中对自旋极化和自旋扩散长度的贡献。铁磁原子向正常金属层的相互扩散形成了一个近藤物理起重要作用的区域，这导致了实验与现有理论之间的差异。我们从一个简单模型出发，构建了一个修正的自旋漂移 - 扩散方程，该方程清楚地表明近藤物理不仅抑制电导率，而且更强烈地减小自旋扩散长度。我们还给出了在一个说明性区域中由于近藤物理导致的自旋极化抑制的显式表达式。我们将该理论与先前的实验数据进行比较，以提取近藤自旋翻转散射的埃利奥特 - 雅费特概率估计值为0.7±0.4，这与近藤原始理论中得出的2/3的值吻合良好。
