Flatte ME, Byers JM
Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242, USA.
Phys Rev Lett. 2000 May 1;84(18):4220-3. doi: 10.1103/PhysRevLett.84.4220.
The behavior of spin diffusion in doped semiconductors is shown to be qualitatively different than in undoped (intrinsic) ones. Whereas a spin packet in an intrinsic semiconductor must be a multiple-band disturbance, involving inhomogeneous distributions of both electrons and holes, in a doped semiconductor a single-band disturbance is possible. For n-doped nonmagnetic semiconductors the enhancement of diffusion due to a degenerate electron sea in the conduction band is much larger for these single-band spin packets than for charge packets-this explains the anomalously large spin diffusion recently observed in n-doped GaAs at 1.6 K. In n-doped ferromagnetic and semimagnetic semiconductors the motion of spin packets polarized antiparallel to the equilibrium carrier spin polarization is predicted to be an order of magnitude faster than for parallel polarized spin packets. These results are reversed for p-doped semiconductors.
结果表明，掺杂半导体中的自旋扩散行为与未掺杂（本征）半导体中的自旋扩散行为在性质上有所不同。在本征半导体中，一个自旋包必定是一个多带扰动，涉及电子和空穴的非均匀分布，而在掺杂半导体中，单带扰动是可能的。对于n型掺杂的非磁性半导体，由于导带中简并电子海导致的扩散增强，对于这些单带自旋包来说，比对电荷包要大得多——这解释了最近在1.6 K下n型掺杂砷化镓中观察到的异常大的自旋扩散。在n型掺杂的铁磁和半磁半导体中，与平衡载流子自旋极化方向反平行极化的自旋包的运动预计比平行极化的自旋包快一个数量级。对于p型掺杂半导体，这些结果是相反的。
