CAREER: Spin-Polarized Transport and Spintronic Devices

本研究的目的是制定铁磁异质结中自旋极化输运的理论框架，并通过开发建模工具，提出和批判性地评估新的自旋电子器件。存储在磁性区域的信息，使用不同的磁化方向，即使不提供任何外部电源，也可以保存，为低功耗和非易失性应用开辟了可能性。然而，现有的基于磁阻效应的商业自旋电子器件只利用了一小部分潜在的基于自旋的应用。在稀磁性半导体和非磁性半导体/金属铁磁结中，铁磁性可以进行光学和电调谐，从而实现新型自旋晶体管和多功能器件，用于存储器和逻辑的无缝集成。该方法是建立一个多尺度模型，该模型结合了漂移扩散方程、广义Landauer-Buttiker形式和第一性原理密度泛函理论，以自一致地处理大量变化的载流子密度、与局部电荷中性的强烈偏差、自旋极化输运和非均匀铁磁性。更广泛的影响拟议的研究将与开发物理课程和广泛的学生培训紧密结合，通过路易斯斯托克斯少数民族参与联盟为本科生积极招募代表性不足的少数民族。PI将开发一门多学科的自旋电子学基础课程，涵盖固态物理、工程、材料科学和纳米技术等方面。为了传播这项研究的成果，并为自旋电子学和相关学科的学生提供更多的机会和培训，PI将与橡树岭国家实验室和田纳西大学合作，共同组织一个关于纳米结构中传输的国际研讨会。

Intellectual MeritThe objective of this research is to formulate a theoretical framework for spin-polarized transport in ferromagnetic heterojunctions and, by developing modeling tools, to propose and critically assess novel spintronic devices. Information stored in magnetic regions, using different orientations of the magnetization, can be preserved even without supplying any external power, opening possibilities for low-power and non-volatile applications. However, the existing commercial spintronic devices, based on the magnetoresistive effects, utilize only a small fraction of potential spin-based applications. In dilute magnetic semiconductors and in nonmagnetic semiconductor/metallic ferromagnet junctions ferromagnetism can be optically and electrically tuned thus enabling novel classes of spin transistors and multifunctional devices for seamless integration of memory and logic. The approach is to develop a multiscale modeling which combines drift-diffusion equations, generalized Landauer-Buttiker formalism, and first-principles density functional theory, to self-consistently treat largely varying carrier densities, strong deviations from the local charge neutrality, spin-polarized transport, and inhomogeneous ferromagnetism. Broader ImpactThe proposed research will be closely integrated with developing physics curricula and an extensive student training with active recruitment of underrepresented minorities through the Louis Stokes Alliance for Minority Participation for undergraduate students. The PI will develop a multidisciplinary course Fundamentals of Spintronics which will span aspects of solid-state physics, engineering, materials science, and nanotechnology. To disseminate the results of this research and provide additional exposure and training of students in spintronics and related disciplines, the PI will co-organize an international workshop on transport in nanostructures in collaborations with the Oak Ridge National Laboratory and the University of Tennessee.