(Ga,Mn)As中电流诱导自旋极化的磁光Kerr测量

在GaAs吸收带边附近, 利用磁光Kerr效应测量了(Ga,Mn)As和p-GaAs样品的电流诱导Kerr旋转谱和反射谱, 两者都呈现出Lorentz曲线形状. 电流诱导Kerr旋转角和反射率随着电流的增大而增大, Kerr角与电流的大小成正比关系, 反射率与电流的平方成正比关系. (Ga,Mn)As的Kerr旋转角比p-GaAs的大了一个数量级, 这说明Mn原子的掺杂使得电流诱导的自旋极化增强. 另外, 还测量了温度和入射光偏振方向对电流诱导Kerr旋转谱和反射谱的影响. 发现随着温度的升高, Kerr谱和反射谱均向长波方向移动, 这与GaAs带边随温度的变化是一致的.

Observation of current-induced polarization in (Ga,Mn)As via magneto-optic Kerr measurement

Current-induced Kerr rotation spectra and reflectivity spectra of (Ga,Mn)As and p-GaAs were measured in the absence of the magnetic field via magneto-optic Kerr effect around the energy gap. The dependence of the Kerr rotation and the reflectivity on the laser wavelength show Lorentzian profile. The Kerr rotation depends linearly on the current and the reflectivity depends linearly on the square of the current. The Kerr rotation of P-GaAs is much weaker than that of the (Ga,Mn)As which indicate that the doping of Mn enhance the current-induced spin polarization . The dependence of the Kerr rotation and the reflectivity on the temperature was also measured, both showing red shift of their Lorentzian peaks, a familiar behavior as the absorption edge of GaAs. In addition, we observed the dependence of the Kerr signal on the polarizational direction of the incident beam.