Bound magnetic polaron interactions in insulating doped diluted magnetic semiconductors
Bound magnetic polaron interactions in insulating doped diluted magnetic semiconductors
复制标题
DOI：
10.1103/physrevb.65.235205
复制
发表时间：
2002-06-15
影响因子：
3.7
通讯作者：
Wolff, PA
中科院分区：
文献类型：
--
作者：
Durst, AC;Bhatt, RN;Wolff, PA
绝缘掺杂稀释磁性半导体（DMS's）的磁性行为是由称为束缚磁极化子的大集体自旋相互作用表征的。对这些材料磁化率的实验测量表明，极化子-极化子相互作用是铁磁性的，而非磁性半导体的特征是反铁磁性载流子-载流子相互作用。为了解释这种行为，已经开发了一个模型，其中极化子通过标准的直接载流子-载流子交换相互作用（由于虚拟载流子跳跃）和间接载流子-离子-载流子交换相互作用（由于极化子与间隙区域中的磁性离子的相互作用）相互作用。采用变分法，确定了模型参数的最优值作为温度的函数。在感兴趣的温度下，描述极化子-极化子相互作用的参数被发现几乎与温度无关。对于这些常数参数的合理取值，我们发现间接铁磁相互作用可以支配直接反铁磁相互作用，并导致极化子排列。这一结果支持了绝缘掺杂DMS铁磁性的实验证据。
The magnetic behavior of insulating doped diluted magnetic semiconductors (DMS's) is characterized by the interaction of large collective spins known as bound magnetic polarons. Experimental measurements of the susceptibility of these materials have suggested that the polaron-polaron interaction is ferromagnetic, in contrast to the antiferromagnetic carrier-carrier interactions that are characteristic of nonmagnetic semiconductors. To explain this behavior, a model has been developed in which polarons interact via both the standard direct carrier-carrier exchange interaction (due to virtual carrier hopping) and an indirect carrier-ion-carrier exchange interaction (due to the interactions of polarons with magnetic ions in an interstitial region). Using a variational procedure, the optimal values of the model parameters were determined as a function of temperature. At temperatures of interest, the parameters describing polaron-polaron interactions were found to be nearly temperature-independent. For reasonable values of these constant parameters, we find that indirect ferromagnetic interactions can dominate the direct antiferromagnetic interactions and cause the polarons to align. This result supports the experimental evidence for ferromagnetism in insulating doped DMS's.