GOALI: Measurement and Control of Spin Dynamics in 6.1-Angstrom Heterostructures

University Of Iowa, Iowa City IA

Investigators

Abstract

This project centers on a comprehensive experimental program aimed at exploring and applying the unusual properties of 6.1-angstrom heterostructures (InAs/GaSb/AlSb) for potential spintronics applications. Novel mid-infrared ultrafast optical tools and techniques will be used to quantify the material properties governing spin dynamics in these heterostructures, including spin relaxation and spin transport, and the results will be used as a basis for spintronic device development. Special emphasis will be placed on spin dynamics in (110)-oriented 6.1-angstrom heterostructures and on the role of interfaces in controlling these dynamics. As was recently demonstrated by the PI and Co-PI, (110)-grown InAs/GaSb superlattices offer significantly enhanced spin lifetimes due to the absence of native interface asymmetry contributions to precessional spin decay, which dominates in corresponding (001) 6.1-A structures. Through a long-standing collaboration with Professor Michael Flatte of the University of Iowa, this experimental program will be coordinated with theoretical calculations of spin-dependent band structures, spin lifetimes, and spin transport. The program will also benefit from several other collaborations, including one with HRL Laboratories, where the first MBE growth of a (110)-oriented InAs/GaSb short-period superlattice was recently demonstrated. The 6.1-angstrom heterostructures are intrinsically interesting owing to their unusual band alignments, strong spin-orbit coupling, novel interface properties, and large electron mobilities. Many of these same properties make these materials intriguing for spintronic device applications. The measurements proposed here will provide a crucial contribution to the state of knowledge regarding spin dynamics in this technologically important system. Our studies of the relationship between spin lifetimes and interface properties in (110)-oriented structures will allow us to explore the extent to which interface control can further enhance spin relaxation times. Such a result would substantially widen the scope of potential spintronics device architectures based on this system. The results will also contribute to broader current research efforts focused on improving interfaces in the 6.1-angstrom heterostructures, which could lead to improvements in advanced electronic and optoelectronic devices, such as resonant interband tunneling diodes and mid-wave and long-wave infrared lasers and detectors. The proposed program, which involves an industrial collaborator, will expose graduate and undergraduate students to a broad range of specialized courses, state-of-the-art laboratory facilities, and a multi-disciplinary research environment, thus providing them with excellent training for careers in either industry or academia. This program will also contribute to the increased participation of women in scientific research, through fostering the academic career ambitions of the Co-PI. The project will support K-12 outreach through its contributions to an established University of Iowa educational program, Family Adventures in Science, a hands-on weekend program targeted at children age 12 and under.