Asymmetric Splitting of Exciton States in Diluted Magnetic Semiconductor Cd1-xMnxS
Asymmetric Splitting of Exciton States in Diluted Magnetic Semiconductor Cd1-xMnxS
复制标题
稀磁半导体Cd1-xMnxS中激子态的不对称分裂
DOI：
10.1143/jpsj.70.2224
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发表时间：
2001
影响因子：
1.7
通讯作者：
Masao Takahashi
中科院分区：
文献类型：
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作者：
Masao Takahashi
在Aii 1 − xMnxB VI稀磁半导体（DMS）中，Cd 1 − xMnxS与其他DMS不同，因为它的（表观）p-d交换积分|N0 β|值比其他DMS的值大得多。1)在Cd1 − xMnxS中实验观察到的各种异常现象正是由大的p-d交换相互作用引起的。在我以前的研究中，通过将相干势近似（CPA）2）应用于DMS中载流子的简单模型，我们计算了带边能量来解释带隙弯曲3）和在x → 0的情况下p-d交换相互作用的明显增强。4)在这项工作中，通过扩展以前的方法，我们打算解释由Gubarev和Tyazhlov观察到的Cd 1 − xMnxS中塞曼能量分量的不对称分裂; 5）当外加磁场时，A激子项的自旋分裂模式相对于无磁场的位置是不对称的。在我们的模型中，3，4）Cd1 − xMnxS被认为是一种半导体合金，其中CdS中的Cd离子（符号：A）的摩尔分数x被Mn离子（符号：M）随机取代。在Cd1 − xMnxS中移动的单个载流子（以下称为空穴）取决于它是在Cd位还是Mn位上而受到局部电势EA或EM-I σ·Sn的影响。这里，EA和EM分别表示Cd离子和Mn离子的化学（或自旋无关）势;-I σ·Sn表示空穴与位于n位的Mn的d自旋算符Sn之间的p-d交换相互作用。CPA是一种上级平均场理论，适用于在单格位近似下描述二元替位合金的电子性质。2)在CPA中，无序势被认为是有效介质的相干势或自能;相干势（ω）是一个依赖于能量（ω）的复势，它被确定为使得载流子在有效介质中嵌入的所选位置处的有效散射平均为零。条件由2 - 4）给出
Among Aii 1− xMnxB VI diluted magnetic semiconductors (DMSs), Cd1− xMnxS is distinguishable from other DMSs because its (apparent) p–d exchange integral| N0β| value is considerably larger than those of other DMSs. 1) It is the large p–d exchange interaction that causes various abnormal phenomena experimentally observed in Cd1− xMnxS. In my previous studies, by applying the coherent potential approximation (CPA) 2) to a simple model for a carrier in DMSs, we calculated the bandedge energy to explain the band-gap bowing 3) and the apparent enhancement of the p–d exchange interaction in the case of x→ 0. 4) In this work, by extending the previous method, we intend to explain asymmetric splitting of Zeeman energy components in Cd1− xMnxS observed by Gubarev and Tyazhlov; 5) when a magnetic field is applied, the pattern of spin splitting of the A exciton term is asymmetric relative to a position without a magnetic field.In our model, 3, 4) Cd1− xMnxS is regarded as a semiconducting alloy in which a mole fraction x of Cd ions (symbol: A) in CdS are replaced at random by Mn ions (symbol: M). A single carrier (hereafter referred to as a hole) moving in Cd1− xMnxS is subjected to the local potential EA or EM-Iσ· Sn depending on whether it is on Cd site or an Mn site. Here, EA and EM denote the chemical (or spin independent) potential for the Cd ion and Mn ion, respectively;-Iσ· Sn represents the p–d exchange interaction between the hole and the d spin operator Sn of Mn located on n site. The CPA is a superior mean-field theory that is applicable to describe the electronic properties of binary substitutional alloys within the single-site approximation. 2) In the CPA, the disordered potential is considered in terms of the effective medium Σ, called the coherent potential or self-energy; Σ≡ Σ (ω) is an energy (ω)-dependent complex potential which is decided such that the effective scattering of a carrier at a chosen site embedded in the effective medium is zero, on average. The condition is given by 2–4)