Dresden 2006 – scientific programme

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MA: Magnetismus

MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)

MA 20.13: Poster

Tuesday, March 28, 2006, 15:15–19:15, P1

Ferromagnetism and magnetotransport in Co-doped ZnO — •Sebastian Bauer, Maike Luebbe, Karl-Wilhelm Nielsen, Matthias Opel, Sebastian T. B. Goennenwein, and Rudolf Gross — Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching

The interest in diluted magnetic semiconductors (DMS) has grown, since they would allow to combine spintronic devices with traditional semiconductors. ZnO:Co is such a DMS, for which a Curie temperature above room temperature has been predicted [1].

We have grown homoepitaxial Co-doped ZnO films on ZnO substrates using pulsed laser deposition at different temperatures (300-600^∘C) and gas atmospheres (Ar, O₂). This allows to control the concentration of impurities, in particular oxygen vacancies. The magnetic properties of the thin films have been analyzed by dc magnetometry and electrical transport measurements.

Our results show that the films are electron doped and exhibit a ferromagnetic coupling that depends on the impurity concentration. The magnetoresistance shows a complex dependence on the orientation of the magnetic field with respect to the crystal axes and the current direction. Moreover, the magnetoresistance strongly depends on the temperature and even changes sign.

This work is supported by the DFG via SPP 1157.

[1] J. M. D. Coey et al., Nature Materials 4, 173 (2005).