Spin Transport in Semiconductors
Physics Colloquium
4:00 pm –
5:00 pm
Jorgensen Hall Room: 136
Co-Sponsored by NCMN
Abstract:
Semiconductors provide a uniquely hospitable environment for electron spins. Mechanisms for relaxation are weak, allowing spins to survive on time scales (nanoseconds) much longer than those typical of charge transport. This makes semiconductors an ideal host, and there are reasonable prospects for controlling spin transport with “knobs” such as the spin-orbit and hyperfine interactions. Given these possibilities, it is a frustrating fact that an external source of spin-polarized electrons is required to exploit these advantages. I will review the progress over the last decade in developing a technology based on the integration of nature’s best source of spin-polarized electrons (ferromagnetic metals) with semiconductors. It is now possible to inject a significant spin-polarized current into semiconductors from a ferromagnetic source and detect it several microns away. I will provide an overview of the materials physics of these devices, along with a discussion of some of the physics they have been able to address.
Bio: Paul Crowell received his PhD in low-temperature physics from Cornell University in 1994 and was a postdoctoral associate at the CNRS, Grenoble and the University of California at Santa Barbara before joining the faculty of the University of Minnesota in 1997. He is currently a Professor of Physics. Professor Crowell’s research focuses on spin dynamics in ferromagnets on sub-nanosecond time scales and spin transport in hybrid ferromagnet-semiconductor and ferromagnet/normal metal systems. He has been a Sloan Research Fellow, a McKnight Land Grant Professor, and a McKnight Presidential Fellow. Professor Crowell has served as General Chair of the Joint MMM/Intermag Conference (2013) and as Chair of the APS Topical Group on Magnetism and Magnetic Materials (2012-2013). He is a fellow of the American Physical Society.
Abstract:
Semiconductors provide a uniquely hospitable environment for electron spins. Mechanisms for relaxation are weak, allowing spins to survive on time scales (nanoseconds) much longer than those typical of charge transport. This makes semiconductors an ideal host, and there are reasonable prospects for controlling spin transport with “knobs” such as the spin-orbit and hyperfine interactions. Given these possibilities, it is a frustrating fact that an external source of spin-polarized electrons is required to exploit these advantages. I will review the progress over the last decade in developing a technology based on the integration of nature’s best source of spin-polarized electrons (ferromagnetic metals) with semiconductors. It is now possible to inject a significant spin-polarized current into semiconductors from a ferromagnetic source and detect it several microns away. I will provide an overview of the materials physics of these devices, along with a discussion of some of the physics they have been able to address.
Bio: Paul Crowell received his PhD in low-temperature physics from Cornell University in 1994 and was a postdoctoral associate at the CNRS, Grenoble and the University of California at Santa Barbara before joining the faculty of the University of Minnesota in 1997. He is currently a Professor of Physics. Professor Crowell’s research focuses on spin dynamics in ferromagnets on sub-nanosecond time scales and spin transport in hybrid ferromagnet-semiconductor and ferromagnet/normal metal systems. He has been a Sloan Research Fellow, a McKnight Land Grant Professor, and a McKnight Presidential Fellow. Professor Crowell has served as General Chair of the Joint MMM/Intermag Conference (2013) and as Chair of the APS Topical Group on Magnetism and Magnetic Materials (2012-2013). He is a fellow of the American Physical Society.