title: Spin-on spintronics: ultrafast electron spin dynamics in ZnO and Zn₁-xCoxO sol-gel films.
abstract: We use time-resolved Faraday rotation spectroscopy to probe the electron spin dynamics in ZnO and magnetically doped Zn(1-x)Co(x)O sol-gel thin films. In undoped ZnO, we observe an anomalous temperature dependence of the ensemble spin dephasing time T(2), i.e., longer coherence times at higher temperatures, reaching T(2) ∼ 1.2 ns at room temperature. Time-resolved transmission measurements suggest that this effect arises from hole trapping at grain surfaces. Deliberate addition of Co(2+) to ZnO increases the effective electron Landé g factor, providing the first direct determination of the mean-field electron-Co(2+) exchange energy in Zn(1-x)Co(x)O (N(0)α = +0.25 ± 0.02 eV). In Zn(1-x)Co(x)O, T(2) also increases with increasing temperature, allowing spin precession to be observed even at room temperature.
authors: Department of Physics and Center for Applied Photonics, University of Konstanz , D-78464 Konstanz, Germany.
authors: Kelly M
authors: KM
authors: Whitaker
authors: Maxim
authors: M
authors: Raskin
authors: Gillian
authors: G
authors: Kiliani
authors: Katja
authors: K
authors: Beha
authors: Stefan T
authors: ST
authors: Ochsenbein
authors: Nils
authors: N
authors: Janssen
authors: Mikhail
authors: M
authors: Fonin
authors: Ulrich
authors: U
authors: Rüdiger
authors: Alfred
authors: A
authors: Leitenstorfer
authors: Daniel R
authors: DR
authors: Gamelin
authors: Rudolf
authors: R
authors: Bratschitsch