Spin injection and spin accumulation in all-metal mesoscopic spin valves
Spin injection and spin accumulation in all-metal mesoscopic spin valves
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DOI：
10.1103/physrevb.67.085319
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发表时间：
2003-02-15
影响因子：
3.7
通讯作者：
van Wees, BJ
中科院分区：
文献类型：
--
作者：
Jedema, FJ;Nijboer, MS;van Wees, BJ
我们研究了具有透明界面的横向铁磁金属-非磁性金属-铁磁金属（F/N/F）自旋阀器件中自旋累积的电注入和检测。不同的铁磁金属、坡莫合金 (Py)、钴 (Co) 和镍 (Ni) 被用作电自旋注入器和探测器。对于非磁性金属，使用铝（Al）和铜（Cu）。我们的多端子几何结构使我们能够通过实验将自旋阀效应与其他磁阻信号（例如各向异性磁阻和霍尔效应）分开。在“非局部”自旋阀测量中，我们能够完全隔离自旋阀信号，并在 T=4.2 K 以及室温 (RT) 下观察到清晰的自旋累积信号。对于铝，我们在 T=4.2 K 和 RT 时分别获得 1.2 µm 和 600 nm 的自旋弛豫长度 (lambda(sf))，而对于铜，我们获得 1.0 µm 和 350 nm。在 RT 下，这些自旋弛豫长度在最大可获得自旋弛豫长度的 2 倍以内，受到电子声子散射的限制。将 Al 和 Cu 薄膜中的自旋弛豫时间 tau(sf) 与巨磁阻 (GMR)、传导电子自旋共振、反弱局域化和超导隧道实验获得的理论和结果进行了比较。将 Py 和 Co 电极产生的自旋阀信号的幅度与 GMR 实验获得的结果进行比较。对于镍电极，没有观察到超出实验精度的自旋信号。
We study the electrical injection and detection of spin accumulation in lateral ferromagnetic-metal-nonmagnetic-metal-ferromagnetic-metal (F/N/F) spin valve devices with transparent interfaces. Different ferromagnetic metals, Permalloy (Py), cobalt (Co), and nickel (Ni), are used as electrical spin injectors and detectors. For the nonmagnetic metal both aluminum (Al) and copper (Cu) are used. Our multiterminal geometry allows us to experimentally separate the spin valve effect from other magnetoresistance signals such as the anisotropic magnetoresistance and Hall effects. In a "nonlocal" spin valve measurement we are able to completely isolate the spin valve signal and observe clear spin accumulation signals at T=4.2 K as well as at room temperature (RT). For aluminum we obtain spin relaxation lengths (lambda(sf)) of 1.2 mum and 600 nm at T=4.2 K and RT, respectively, whereas for copper we obtain 1.0 mum and 350 nm. At RT these spin relaxation lengths are within a factor of 2 of the maximal obtainable spin relaxation length, being limited by electron-phonon scattering. The spin relaxation times tau(sf) in the Al and Cu thin films are compared with theory and results obtained from giant magnetoresistance (GMR), conduction electron spin resonance, antiweak localization, and superconducting tunneling experiments. The magnitudes of the spin valve signals generated by the Py and Co electrodes are compared to the results obtained from GMR experiments. For the Ni electrodes no spin signal could be observed beyond experimental accuracy.