Ballistic spin filtering across ferromagnet/semiconductor interfaces at room temperature
Ballistic spin filtering across ferromagnet/semiconductor interfaces at room temperature
复制标题
室温下铁磁体/半导体界面的弹道自旋过滤
DOI：
10.1103/physrevb.66.035330
复制
发表时间：
2002
影响因子：
3.7
通讯作者：
S. Holmes
中科院分区：
文献类型：
--
作者：
A. Hirohata;S. J. Steinmueller;W. Cho;Yongbing Xu;C. M. Guertler;G. Wastlbauer;J. Bland;S. Holmes
利用圆偏振光在室温下在铁磁体/ GaAs肖特基二极管结构中产生自旋极化电子（自旋极化方向垂直于薄膜平面）。使用各种铁磁材料（NiFe，Co和Fe）和GaAs掺杂密度的螺旋度依赖的光电流的肖特基势垒的依赖性。在所有情况下，在反向偏置时，铁磁层的磁化重新排列从垂直到平行于光子螺旋度的螺旋度相关的光电流的变化。这种效应是由于自旋分裂态密度在费米能级的铁磁体中发生时，磁化与光子螺旋对准的GaAs中产生的光激发电子的自旋过滤。NiFe表现出明显的自旋过滤，Fe根据肖特基势垒强度表现出强或弱的自旋过滤，而Co几乎没有表现出任何自旋过滤。反铁磁Cr/GaAs显示没有自旋相关的影响，如预期的。这些自旋输运效应在所有情况下消失非常高的掺杂由于肖特基势垒的崩溃。随着光子能量接近GaAs的能隙，GaAs中与光致自旋极化相关的效应变得更大，证实极化电子首先在半导体中被激发，然后被铁磁层过滤。在所有情况下的自旋过滤效应增加铁磁层厚度，并远远大于估计的坡莫合金的磁圆二色性。这些结果明确地表明，高效的自旋从半导体到铁磁体的传输发生在室温下，并在反向偏压下发生强自旋过滤。
Circularly polarized light was used to generate spin-polarized electrons at room temperature in ferromagnet/ GaAs Schottky diode structures (with spin polarization perpendicular to the film plane). The Schottky barrier dependence of the helicity-dependent photocurrent was observed using various ferromagnetic materials (NiFe, Co, and Fe) and GaAs doping densities. A change in the helicity-dependent photocurrent was obtained in all cases in reverse bias when the ferromagnetic layer magnetization was realigned from perpendicular to parallel to the photon helicity. This effect is attributed to spin filtering of photoexcited electrons generated in the GaAs due to the spin split density of states at the Fermi level in the ferromagnet which occurs when the magnetization is aligned with the photon helicity. NiFe shows significant spin filtering, Fe shows either strong or weak spin filtering according to the Schottky barrier strength, while Co shows almost none. Antiferromagnetic Cr/GaAs shows no spin-dependent effects as expected. These spin transport effects in all cases vanish for very high doping due to the collapse of the Schottky barrier. As the photon energy approaches the energy gap of the GaAs, the effects associated with the optically induced spin polarization in the GaAs become larger, confirming that polarized electrons are first excited in the semiconductor and then filtered by the ferromagnetic layer. The spin filtering effects in all cases increase with increasing ferromagnetic layer thickness, and are much larger than the estimated magnetocircular dichroism in permalloy. These results unambiguously indicate that highly efficient spin transport from the semiconductor to the ferromagnet occurs at room temperature and that strong spin filtering occurs in reverse bias.
影响因子：
8.6
作者：
Kikkawa, JM;Awschalom, DD
通讯作者：
Awschalom, DD