非简并p型Hg1-xMnxTe单晶(x>0.17)的负磁电阻机理研究

研究磁性半导体中负磁电阻产生机理对正确理解载流子与磁性离子间的sp-d磁交换作用 是非常重要的.通过变温(10---300 K)磁输运和变温(5---300 K)磁化率实验研究了一系列不同Mn含量 非简并p型Hg_1-xMn_xTe单晶(x>0.17)的负磁电阻和顺磁增强效应. 实验结果表明其负磁电阻与温度的关系和磁化率与温度的关系基本一致, 两者都包含一个呈指数型变化的温度函数exp(-K/T).根据磁性半导体的杂质能级理论, 非简并p型Hg_1-xMn_xTe单晶在低磁场范围内出现负磁电阻效应的主要物理机理 为外磁场的磁化效应使得受主杂质或受主型束缚磁极化子的有效电离能减小.

The mechanism of negative magnetoresistance in nondegenerate p-type Hg1-xMnxTe (x>0.17) monocrystal

It is important to study the mechanism of negative magnetoresistance (MR) in magnetic semiconductors for the correct understanding of the sp-d interactions between carriers and magnetic ions. In this work, temperature-dependent Hall effect (10---300 K) and magnetic susceptibility (5---300 K) are measured for the study of negative MR and paramagnetic enhancement of nondegenerate p-type Hg_1-xMn_xTe (x>0.17) monocrystal. As temperature decreases, both negative MR and susceptibility show the same behaviors, each of which contains an exponentially changing temperature function \exp(-K/T). According to the theory of impurity energy level in semimagnetic semiconductor, magnetic field can lead to the spin-splitting of acceptor level and result in reducing the binding energy of acceptors, which is responsible mainly for the negative MR in nondegenerate p-type Hg_1-xMn_xTe monocrystal.