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MA: Fachverband Magnetismus

MA 7: Magnetic Semiconductors

MA 7.7: Talk

Monday, March 16, 2015, 13:00–13:15, EB 202

Structure and magnetism of the Zn-Co-O system: From n-type wurtzite Co:ZnO to p-type spinel ZnCo₂O₄ — •Bastian Henne¹, Verena Ney¹, Mariano de Souza¹, Katharina Ollefs², Fabrice Wilhelm², Andrei Rogalev², and Andreas Ney¹ — ¹Johannes Kepler Universität, Linz - Austria — ²European Synchrotron Radiation Facility, Grenoble - France

The combined optical and transport properties of oxide semiconductors such as cobalt doped ZnO (Co:ZnO) and the related spinel ZnCo₂O₄ are of potential interest for applications. However, while the magnetic properties of Co:ZnO were subject of intense research activities, the magnetism of the spinel system ZnCo₂O₄ received only little attention so far (1). In this contribution we present the growth of both; phase pure n-type wurtzite Co:ZnO with extremely high Co content and p-type spinel ZnCo₂O₄ from a single oxide composite target by reactive magnetron sputtering. The structural properties were investigated by XRD and synchrotron techniques as XAS and XLD. The magnetic properties were analyzed by integral SQUID magnetometry down to 2 K and up to 5 T and using element specific XMCD up to 17 T. We see indications of uncompensated antiferromagnetism (2) well below room temperature for both systems and the low temperature M(H)-hystereses show history dependent behavior being reminiscent of an exchange bias.

(1) H.J. Kim, et al., J. Appl. Phys. 95, 7387 (2004).

(2) A. Ney et al., Phys. Rev. B 85, 245202 (2012).