title: Co-occurrence of superparamagnetism and anomalous hall effect in highly reduced cobalt-doped rutile TiO2-delta films.
abstract: We report a detailed magnetic and structural analysis of highly reduced Co doped rutile TiO(2-delta) films displaying an anomalous Hall effect (AHE). The temperature and field dependence of magnetization, and transmission electron microscopy, clearly establish the presence of nanosized superparamagnetic cobalt clusters of approximately 8-10 nm size in the films at the interface. The co-occurrence of superparamagnetism and AHE raises questions regarding the use of the AHE as a test of the intrinsic nature of ferromagnetism in diluted magnetic semiconductors.
authors.affiliation: Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA. shinde@squid.umd.edu
authors.forename: S R
authors.initials: SR
authors.lastname: Shinde
authors.forename: S B
authors.initials: SB
authors.lastname: Ogale
authors.forename: J S
authors.initials: JS
authors.lastname: Higgins
authors.forename: H
authors.initials: H
authors.lastname: Zheng
authors.forename: A J
authors.initials: AJ
authors.lastname: Millis
authors.forename: V N
authors.initials: VN
authors.lastname: Kulkarni
authors.forename: R
authors.initials: R
authors.lastname: Ramesh
authors.forename: R L
authors.initials: RL
authors.lastname: Greene
authors.forename: T
authors.initials: T
authors.lastname: Venkatesan