Doppler velocimetry of spin propagation in a two-dimensional electron gas

TL;DR

This paper uses Doppler velocimetry to study spin propagation in GaAs quantum wells, revealing temperature-dependent behavior of spin mobility and the breakdown of coherent spin precession above 150 K, impacting spintronic device development.

Contribution

It demonstrates the application of Doppler velocimetry to measure spin dynamics in high mobility semiconductors and uncovers temperature limits for coherent spin precession.

Findings

Spin mobility matches electron mobility across temperatures.

Coherent spin precession breaks down above 150 K.

Temperature-dependent spin dynamics impact spintronic devices.

Abstract

Controlling the flow of electrons by manipulation of their spin is a key to the development of spin-based electronics. While recent demonstrations of electrical-gate control in spin-transistor configurations show great promise, operation at room temperature remains elusive. Further progress requires a deeper understanding of the propagation of spin polarization, particularly in the high mobility semiconductors used for devices. Here we report the application of Doppler velocimetry to resolve the motion of spin-polarized electrons in GaAs quantum wells driven by a drifting Fermi sea. We find that the spin mobility tracks the high electron mobility precisely as a function of T. However, we also observe that the coherent precession of spins driven by spin-orbit interaction, which is essential for the operation of a broad class of spin logic devices, breaks down at temperatures above 150 K for reasons that are not understood theoretically.