Charge Transport in the Impurity Band of Dilute Magnetic Semiconductors: Experiment and Theory

稀磁半导体杂质带中的电荷传输：实验与理论

• 批准号: 194176975
• 负责人: Professor Dr. Sergei Baranovski
• 金额: --
• 依托单位: I. Physikalisches Institut
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/194176975?language=en
• 关键词: Charge; Transport; Impurity; Band; Dilute

By incorporating magnetic atoms into conventionally doped semiconductors one enters an interesting field between magnetism and semiconductor physics. On the one hand, in dilute magnetic semiconductors (DMS) such as Zn1-xMnxSe:Cl, spin-effects on the electronic structure can be tuned continuously up to orders of magnitude by varying x. On the other hand, the evolution of the Cl-donor energy levels into a so called impurity band (IB) by varying the donor concentration ND provides an excellent test-ground for verifying fundamental physical concepts of charge transport in solid media. DMS show a very different transport behavior compared to non-magnetic systems. This holds for both regimes on either side of the metal-insulator transition (MIT) – hopping conductivity at low donor concentrations and metallic conductivity at high doping levels. These differences must arise from the interplay of enhanced spin effects in the scattering processes, in the shape of the donor wave functions, and in the spin-dependent changes of the density of states of impurity and conduction bands. However, conventional models cannot account for the observed behavior. Most theories of charge transport are applicable only to non-magnetic systems assuming that the impurity levels are spin-degenerate and independent of external magnetic field. We will perform low-temperature magneto-transport and magneto-optical spectroscopic measurements on different series of n-type Zn1-xMnxSe, which is an ideal model system as concentrations x and ND can be varied independently. The experimental study will be combined with the development of an adequate transport theory to model the experimental results and, thus, to clarify the fundamental problems of charge transport and MIT in DMS.

通过将磁性原子掺入常规掺杂的半导体中，人们进入了磁性和半导体物理之间的一个有趣的领域。一方面，在稀磁半导体（DMS），如Zn 1-xMnxSe：Cl，电子结构上的自旋效应可以通过改变x连续调谐到数量级。另一方面，通过改变供体浓度ND，Cl-供体能级演变为所谓的杂质带（IB），为验证固体介质中电荷传输的基本物理概念提供了良好的测试基础。与非磁性系统相比，DMS显示出非常不同的输运行为。这适用于在低施主浓度下的金属-绝缘体转变（MIT）跳跃电导率和在高掺杂水平下的金属电导率的任一侧上的两种制度。这些差异一定是由于散射过程中增强的自旋效应的相互作用、施主波函数的形状以及杂质和导带的态密度随自旋的变化引起的。然而，传统的模型不能解释所观察到的行为。大多数电荷输运理论仅适用于非磁性系统，假设杂质能级是自旋简并的，与外磁场无关。我们将对不同系列的n型Zn_（1-x）Mn_xSe进行低温磁输运和磁光光谱测量，这是一个理想的模型系统，因为浓度x和ND可以独立变化。实验研究将结合适当的传输理论的发展，模拟实验结果，从而澄清DMS中的电荷传输和MIT的基本问题。

项目成果

Scaling approach to hopping magnetoresistivity in dilute magnetic semiconductors

稀磁半导体中跳跃磁阻的缩放方法

• DOI: 10.1103/physrevb.88.115210
• 发表时间: 2013
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: A. V. Nenashev;F. Jansson;M. Wiemer;S. Petznick;P. J. Klar;M. Hetterich;A. V. Dvurechenskii;F. Gebhard;S. D. Baranovskii
• 通讯作者: S. D. Baranovskii

Large positive magnetoresistance effects in the dilute magnetic semiconductor (Zn,Mn)Se in the regime of electron hopping

• DOI: 10.1063/1.4894236
• 发表时间: 2014-08
• 期刊: Journal of Applied Physics
• 影响因子: 3.2
• 作者: F. Jansson;M. Wiemer;A. Nenashev;S. Petznick;P. Klar;M. Hetterich;F. Gebhard;S. Baranovskii

Scaling description of positive magnetoresistivity in doped dilute magnetic semiconductors

掺杂稀磁半导体中正磁阻的缩放描述

• DOI: 10.1016/j.jmmm.2014.11.069
• 发表时间: 2015
• 期刊: Journal of Magnetism and Magnetic Materials
• 影响因子: 2.7
• 作者: A. V. Nenashev; F. Jansson;S. Petznick;M. Wiemer;P.J. Klar;A. V. Dvurechenskii;F. Gebhard;S. D. Baranovskii
• 通讯作者: S. D. Baranovskii