Effects of exchange and electron correlation on conductance and nanomagnetism in ballistic semiconductor quantum point contacts
Effects of exchange and electron correlation on conductance and nanomagnetism in ballistic semiconductor quantum point contacts
复制标题
交换和电子关联对弹道半导体量子点接触中电导和纳米磁性的影响
DOI：
10.1103/physrevb.66.085323
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发表时间：
2002
影响因子：
3.7
通讯作者：
I. Yakimenko
中科院分区：
文献类型：
--
作者：
K. Berggren;I. Yakimenko
研究了GaAs/AlxGa 1-xAs异质结中高迁移率二维电子气横向约束下两个大量子点之间形成的量子点接触的自发磁化。该器件的模型结合了图案化栅极、掺杂、表面态和镜像电荷的贡献。为了探索磁性，科恩-沙姆局部自旋密度形式主义与交换和相关势，允许局部自旋极化。交换是QPC中局部磁化的主要机制，而相关部分不太突出。然而，相关电位引起QPC电位的重要修正。因此，在第一个传导平台之下，我们发现了一个磁化机制，它大约对应于一个单电子自旋。利用近似的可分鞍势，我们计算了电导，并恢复了所谓的近似0.7（2 e（2）/h）的电导异常，加上近似0.4（2 e（2）/h）的额外异常，低于该异常时，磁化强度崩溃。
The spontaneous magnetization of a quantum point contact (QPC) formed between two large quantum dots by a lateral confinement of a high-mobility two-dimensional electron gas is studied for a realistic GaAs/AlxGa1-xAs heterostructure. The model of the device incorporates the contributions from a patterned gate, doping, surface states, and mirror charges. To explore the magnetic properties, the Kohn-Sham local spin-density formalism is used with exchange and correlation potentials that allows for local spin polarization. Exchange is the dominant mechanism behind local magnetization within the QPC, while the correlation part is less prominent. However, the correlation potential gives rise to an important correction in the QPC potential. Below the first conduction plateau we thus find a magnetized regime corresponding approximately to a single electron spin. Using an approximate separable saddle potential we compute the conductance and recover the so-called similar to0.7 (2e(2)/h) conduction anomaly plus an additional anomaly at similar to0.4 (2e(2)/h) below which the magnetization collapses.