title: Gate-voltage control of spin interactions between electrons and nuclei in a semiconductor.
abstract: Semiconductors are ubiquitous in device electronics, because their charge distributions can be conveniently manipulated with voltages to perform logic operations. Achieving a similar level of control over the spin degrees of freedom, either from electrons or nuclei, could provide intriguing prospects for both information processing and the study of fundamental solid-state physics issues. Here we report procedures that carry out the controlled transfer of spin angular momentum between electrons-confined to two dimensions and subjected to a perpendicular magnetic field-and the nuclei of the host semiconductor, using gate voltages only. We show that the spin transfer rate can be enhanced near a ferromagnetic ground state of the electron system, and that the induced nuclear spin polarization can be subsequently stored and 'read out'. These techniques can also be combined into a spectroscopic tool to detect the low-energy collective excitations in the electron system that promote the spin transfer. The existence of such excitations is contingent on appropriate electron-electron correlations, and these can be tuned by changing, for example, the electron density via a gate voltage.
authors.affiliation: Max-Planck-Institut für Festkörperforschung, D-70569 Stuttgart, Germany. j.smet@fkf.mpg.de
authors.forename: J H
authors.initials: JH
authors.lastname: Smet
authors.forename: R A
authors.initials: RA
authors.lastname: Deutschmann
authors.forename: F
authors.initials: F
authors.lastname: Ertl
authors.forename: W
authors.initials: W
authors.lastname: Wegscheider
authors.forename: G
authors.initials: G
authors.lastname: Abstreiter
authors.forename: K
authors.initials: K
authors.lastname: von Klitzing