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

Case Western Reserve University, Cleveland OH

Investigators

Abstract

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-collinear magnetism 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 effect will be developed.