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arXiv 0809.1120cond-mat.mtrl-sci
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铁磁/半导体电自旋探测器的偏压控制灵敏度

Bias-controlled sensitivity of ferromagnet/semiconductor electrical spin detectors

S. A. Crooker, E. Garlid, A. N. Chantis, D. L. Smith, K. S. M. Reddy, Q. Hu, T. Kondo, C. J. Palmstrom, P. A. Crowell

摘要:

使用Fe/GaAs肖特基隧道势垒作为电自旋探测器,我们表明,它们的自旋检测灵敏度的幅度和符号可以广泛地调整与跨越Fe/GaAs界面施加的电压偏置。实验和理论证实,这种可调谐性不仅来源于隧穿电导$G_{\uparrow,\downarrow}$(界面的性质)的偏压依赖性,而且来源于半导体中电场的偏压依赖性,这可以显著地增强或抑制自旋检测灵敏度。因此,可以使GaAs中具有固定极化的电子在自旋检测器处引起正或负电压变化,并且与零偏置自旋检测的通常情况相比,某些检测器的灵敏度可以提高十倍以上。

英文摘要:

Using Fe/GaAs Schottky tunnel barriers as electrical spin detectors, we show that the magnitude and sign of their spin-detection sensitivities can be widely tuned with the voltage bias applied across the Fe/GaAs interface. Experiments and theory establish that this tunability derives not just simply from the bias dependence of the tunneling conductances $G_{\uparrow,\downarrow}$ (a property of the interface), but also from the bias dependence of electric fields in the semiconductor which can dramatically enhance or suppress spin-detection sensitivities. Electrons in GaAs with fixed polarization can therefore be made to induce either positive or negative voltage changes at spin detectors, and some detector sensitivities can be enhanced over ten-fold compared to the usual case of zero-bias spin detection.

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