Kawakami R K, Kato Y, Hanson M, Malajovich I, Stephens J M, Johnston-Halperin E, Salis G, Gossard A C, Awschalom D D
Department of Physics and, Materials Department, University of California, Santa Barbara, CA 93106, USA.
Science. 2001 Oct 5;294(5540):131-4. doi: 10.1126/science.1063186.
We examine how a ferromagnetic layer affects the coherent electron spin dynamics in a neighboring gallium arsenide semiconductor. Ultrafast optical pump-probe measurements reveal that the spin dynamics are unexpectedly dominated by hyperpolarized nuclear spins that align along the ferromagnet's magnetization. We find evidence that photoexcited carriers acquire spin-polarization from the ferromagnet, and dynamically polarize these nuclear spins. The resulting hyperfine fields are as high as 9000 gauss in small external fields (less than 1000 gauss), enabling ferromagnetic control of local electron spin coherence.
我们研究了铁磁层如何影响相邻砷化镓半导体中的相干电子自旋动力学。超快光泵浦-探测测量表明，自旋动力学意外地由沿铁磁体磁化方向排列的超极化核自旋主导。我们发现有证据表明光激发载流子从铁磁体获得自旋极化，并动态极化这些核自旋。在小外部磁场（小于1000高斯）中，产生的超精细场高达9000高斯，从而实现对局部电子自旋相干性的铁磁控制。
