title: Impurity-assisted tunneling magnetoresistance under a weak magnetic field.
abstract: Injection of spins into semiconductors is essential for the integration of the spin functionality into conventional electronics. Insulating layers are often inserted between ferromagnetic metals and semiconductors for obtaining an efficient spin injection, and it is therefore crucial to distinguish between signatures of electrical spin injection and impurity-driven effects in the tunnel barrier. Here we demonstrate an impurity-assisted tunneling magnetoresistance effect in nonmagnetic-insulator-nonmagnetic and ferromagnetic-insulator-nonmagnetic tunnel barriers. In both cases, the effect reflects on-off switching of the tunneling current through impurity channels by the external magnetic field. The reported effect is universal for any impurity-assisted tunneling process and provides an alternative interpretation to a widely used technique that employs the same ferromagnetic electrode to inject and detect spin accumulation.
authors.affiliation: CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country, Spain.
authors.forename: Oihana
authors.initials: O
authors.lastname: Txoperena
authors.affiliation: Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Song
authors.affiliation: Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA.
authors.forename: Lan
authors.initials: L
authors.lastname: Qing
authors.affiliation: CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country, Spain and Université de Strasbourg, Institut de Science et d'Ingénierie Supramoléculaires (I.S.I.S.), 67083 Strasbourg, France.
authors.forename: Marco
authors.initials: M
authors.lastname: Gobbi
authors.affiliation: CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country, Spain and IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Basque Country, Spain.
authors.forename: Luis E
authors.initials: LE
authors.lastname: Hueso
authors.affiliation: Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627, USA and Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA.
authors.forename: Hanan
authors.initials: H
authors.lastname: Dery
authors.affiliation: CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country, Spain and IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Basque Country, Spain.
authors.forename: Fèlix
authors.initials: F
authors.lastname: Casanova