磁场对GaAsN合金自旋过滤效应的放大作用
Amplification of spin-filtering effect by magnetic field in GaAsN alloys
摘要：
我们发现室温下用圆偏振光激发GaAsN合金的边缘光致发光的强度$I$和圆偏振度$ρ$在1，kG量级的纵向磁场$B$中显著增长。这种增加取决于泵浦的强度，并且在弱或中等强度的区域中，可以达到两倍的值。在考虑自旋取向的自由电子在深顺磁中心上自旋相关复合的双电荷态模型中，考虑了磁场对束缚在中心上的电子自旋弛豫的抑制。该模型定性地描述了不同泵浦强度下，$ρ$和$I$在磁场中的上升过程。实验依赖性$ρ(B)$和$I(B)$相对于磁场的零点偏移了$\sim$ 170\，高斯，而偏移的方向随着泵浦圆偏振的符号的改变而反转。作为一个可能的原因，我们认为发现的转变，欧弗豪泽场，所产生的超精细相互作用的电子绑定在一个中心与原子核的晶格在附近的中心。
英文摘要：
We have found that intensity $I$ and circular polarization degree $ρ$ of the edge photoluminescence, excited in GaAsN alloys by circularly polarized light at room temperature, grow substantially in the longitudinal magnetic field $B$ of the order of 1\,kG. This increase depends on the intensity of pumping and, in the region of weak or moderate intensities, may reach a twofold value. In two-charge-state model, which considers spin-dependent recombination of spin-oriented free electrons on deep paramagnetic centers, we included the magnetic-field suppression of spin relaxation of the electrons bound on centers. The model describes qualitatively the rise of $ρ$ and $I$ in a magnetic field under different pump intensities. Experimental dependences $ρ(B)$ and $I(B)$ are shifted with respect to zero of the magnetic field by a value of $\sim$170\,Gauss, while the direction of the shift reverses with change of the sign of circular polarization of pumping. As a possible cause of the discovered shift we consider the Overhauser field, arising due to the hyperfine interaction of an electron bound on a center with nuclei of the crystal lattice in the vicinity of the center.
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