Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 50: Poster II

MA 50.64: Poster

Freitag, 15. März 2013, 10:30–13:30, Poster D

Zinc ferrite, an oxide for spintronics? — •Michael Bonholzer, Kerstin Brachwitz, Annette Setzer, Pablo Esquinazi, Michael Lorenz, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Linnéstr. 5, 04103 Leipzig

Bulk zinc ferrite is known as an antiferromagnetic insulator with normal spinel structure [1,2]. But in thin films grown by pulsed laser deposition, semiconducting behaviour of the conductivity is found [1,3]. The conductivity can be tuned over several orders of magnitude by changing the growth conditions [3]. Magnetism in thin films is also affected by growth conditions and shows different properties compared to bulk as well. Zinc ferrite thin films have a ferrimagnetic magnetisation curve with a high saturation magnetisation and a coercive field of about 10 mT at room temperature. Curie temperature is expected to be well above 800 K [2,3]. The unexpected properties can be explained by disorder caused by oxygen vacancies [3]. Also theoretical calculations show the semiconducting and ferrimagnetic behaviour of slightly distorted zinc ferrite. They also predict a high spin polarisation [4].
The properties make zinc ferrite a promising material for spintronic applications. First results on magnetic tunnel junctions consisting of a zinc ferrite bottom electrode, a magnesium oxide barrier and a cobalt top electrode show a tunnel magnetoresistance up to 25%.
[1] A. Marcu et al., J. Appl. Phys. 102, 023713 (2007)
[2] C.E. Rodríguez Torres et al., Phys. Rev. B 84, 064404 (2011)
[3] M. Lorenz et al., Phys. Status Solidi RRL 5, 438 (2011)
[4] S. Soliman et al., Phys. Rev. B 83, 085205 (2011)