Condensed Matter & Surface Sciences

COLLOQUIUM

Philippe Debray

University of Cincinnati

“All-Electric Quantum Point Contact Spin Polarizer:

From Spin Physics to Spin Electronics”

The controlled creation, manipulation, and detection of spin polarized currents by purely electrical means remains a central challenge of spintronics. One approach to meet this challenge has been to rely on coupling of the electron orbital motion to its spin. Attempts have been made to use the Rashba spin-orbit coupling as a tool to achieve these objectives. Despite intense effort there has so far been no report of any success. Recently, it has been theoretically shown that the in-plane electric field due to the gradients of the confining potential of a current-carrying quantum wire with high intrinsic spin-orbit coupling can cause the accumulation of opposite spins at opposite edges of the wire, though not a net spin-polarized current. In this talk I will present experimental evidence that a quantum point contact made from a semiconductor with high intrinsic spin-orbit coupling can generate completely spin-polarized current when its lateral confinement is made highly asymmetric by tuning the bias voltages of the side gates that create it. By avoiding the use of ferromagnetic contacts or external magnetic fields, the use of such quantum point contacts may make feasible the development of a variety of semiconductor spintronic devices.

Thursday, September 10, 2009

4:10 p.m. -- Walter Lecture Hall 245