Tran M, Jaffrès H, Deranlot C, George J-M, Fert A, Miard A, Lemaître A
Unité Mixte de Physique CNRS-Thales, Route départementale 128, 91767 Palaiseau Cedex and Université Paris-Sud 91405, Orsay, France.
Phys Rev Lett. 2009 Jan 23;102(3):036601. doi: 10.1103/PhysRevLett.102.036601.
We report on spin injection experiments at a Co/Al2O3/GaAs interface with electrical detection. The application of a transverse magnetic field induces a large voltage drop DeltaV at the interface as high as 1.2 mV for a current density of 0.34 nA.microm(-2). This represents a dramatic increase of the spin accumulation signal, well above the theoretical predictions for spin injection through a ferromagnet/semiconductor interface. Such an enhancement is consistent with a sequential tunneling process via localized states located in the vicinity of the Al2O3/GaAs interface. For spin-polarized carriers these states act as an accumulation layer where the spin lifetime is large. A model taking into account the spin lifetime and the escape tunneling time for carriers traveling back into the ferromagnetic contact reproduces accurately the experimental results.
我们报道了在Co/Al2O3/GaAs界面进行的自旋注入实验，并采用电学检测方法。施加横向磁场会在界面处引起高达1.2 mV的大电压降ΔV，对应电流密度为0.34 nA·μm⁻²。这表明自旋积累信号显著增加，远高于通过铁磁体/半导体界面进行自旋注入的理论预测值。这种增强与通过位于Al2O3/GaAs界面附近的局域态的顺序隧穿过程相一致。对于自旋极化载流子，这些态充当自旋寿命较长的积累层。一个考虑了自旋寿命以及载流子返回铁磁接触的逃逸隧穿时间的模型准确地再现了实验结果。
