SPIN ELECTRONICS: Electronic and Magneto-Optic Properties of Rare-Earth and Transition Metal based Materials for Spintronics

该提案是根据21世纪自旋电子学倡议项目招标NSF-02-036收到的。该提案侧重于研究新型磁电子和磁光材料以及需要开发的计算方法以了解其性质。基于稀土（RE）化合物如GdN和过渡金属（TM）和/或稀土掺杂半导体ScN的替代磁性半导体的潜力。相关的金属化合物，如Mn-N化合物也将被研究。预计稀土和TM原子磁耦合性质的不同，将使两者结合时的磁效应增强。这类材料的主要优点是：1)由于常见的岩盐结构而具有完全的互溶性；2)TM和RE交换相互作用和磁矩的互补特性；3)n型自旋电子学的可能性。研究这些材料与高温半导体氮化镓的异质结构。为了更好地理解这些和更传统的磁性半导体的磁性起源，提出了一种基于筛选交换法的新的计算方法。该方法将扩展到能够处理半导体带隙问题和强相关窄带开壳系统，并将在线性松饼锡轨道带结构方法的背景下实现。它将进一步与基于原子球内的刚性自旋近似的非共线磁性方法兼容。计算将提供有关所研究系统的电子结构、起源和磁性性质的信息。为了验证新方法，它将首先应用于已经有实验数据的系统，随后将用于新材料的预测特性。为了帮助与实验数据进行比较，将计算磁光性质以及基本电子结构和磁交换相互作用。将扩展现有的光学计算方法，以纳入新的筛选交换方法，并将其应用于磁光性质，如磁光克尔效应和法拉第旋转效应。

This proposal was received in response to the Spin Electronics for the 21st century Initiative, Program Solicitation NSF-02-036. The proposal focuses on the study of novel magneto-electronic and magneto-optic materials and the computational methods that need to be developed to understand their properties. The potential of alternative magnetic semiconductors based on rare-earth (RE) compounds such as GdN and Transition metal (TM) and/or RE doped semiconducting ScN. Related metallic compounds, such as Mn-N compounds will also be studied. It is anticipated that the different nature of magnetic couplings of RE and TM atoms will enhance the magnetic effects when the two are combined. The main perceived advantage of the class of materials are: 1) full intersolubility because of the common rocksalt structure, 2) the complementary character of TM and RE exchange interactions and magnetic moments, 3) the possibility of n-type based spintronics. Heterostructures of these materials with the compatible high temperature semiconductor GaN will be studied.To develop a better understanding of the origin of magnetism in these and more traditional magnetic semiconductors, a new computational approach is proposed, based on the screened exchange method. This method will be extended to be capable of dealing with both the band gap problem of semiconductors and strongly correlated narrow band open shell systems and will be implemented within the context of the linear muffin-tin orbital band structure method. It will further be made compatible with the non-collinearmagnetism approach based on the rigid spin approximation within atomic spheres.The calculations will provide information on the electronic structure and on the origin and the nature of the magnetism in the systems under study. To validate the new method, it will first be applied to systems for which experimental data are available already and subsequently will be used in a predictive character for new materials. To aid in the comparison with experimental data, magneto-optical properties will be calculated as well as basic electronic structure and magnetic exchange interactions. Extensions of currently available optical calculation methods to incoporate the new screened exchange methodology and its application to magneto-optical properties such as the magneto-optical Kerr effect and the Faraday rotation effectwill be developed.