title: Hydrogen control of ferromagnetism in a dilute magnetic semiconductor.
abstract: We show that upon exposure to a remote dc hydrogen plasma, the magnetic and electronic properties of the dilute magnetic semiconductor Ga1-xMnxAs change qualitatively. While the as-grown Ga1-xMnxAs thin films are ferromagnetic at temperatures T less, similar 70 K, the samples are found to be paramagnetic after the hydrogenation, with a Brillouin-type magnetization curve even at T=2 K. Comparing magnetization and electronic transport measurements, we conclude that the density of free holes p is significantly reduced by the plasma process, while the density of Mn magnetic moments does not change.
authors.affiliation: Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, D-85748 Garching, Germany. goennenwein@tnw.tudelft.nl
authors.forename: Sebastian T B
authors.initials: ST
authors.lastname: Goennenwein
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Wassner
authors.forename: Hans
authors.initials: H
authors.lastname: Huebl
authors.forename: Martin S
authors.initials: MS
authors.lastname: Brandt
authors.forename: Jan B
authors.initials: JB
authors.lastname: Philipp
authors.forename: Matthias
authors.initials: M
authors.lastname: Opel
authors.forename: Rudolf
authors.initials: R
authors.lastname: Gross
authors.forename: Achim
authors.initials: A
authors.lastname: Koeder
authors.forename: Wladimir
authors.initials: W
authors.lastname: Schoch
authors.forename: Andreas
authors.initials: A
authors.lastname: Waag