Above Room Temperature Ferromagnetism in Dilute Magnetic Oxide Semiconductors


Above Room Temperature Ferromagnetism in Dilute Magnetic Oxide Semiconductors

Semisalova, A. S.; Orlov, A.; Smekhova, A.; Gan’Shina, E.; Perov, N.; Anwand, W.; Potzger, K.; Lähderanta, E.; Granovsky, A.

In this chapter, we will survey early and recent experimental results on magnetic properties of dilute magnetic oxide semiconductors, focusing on TiO2-δ:Co and TiO2-δ:V. Room temperature ferromagnetism was observed in both types of thin film samples fabricated by RF sputtering, but their magnetic properties appeared to be quite different. Magnetic moments in case of TiO2-δ:Co are mostly associated with local polarization of Co ions and induced defects. There is an evidence of intrinsic ferromagnetism in the case of low Co content (<1 at.%). Room temperature ferromagnetism was observed in TiO2-δ:V at V content from 3 up to 18 at.% in the whole resistivity range from 10e-3 up to 10e6 Ω cm. Positron annihilation spectroscopy revealed a correlation between magnetization and concentration of the negatively charged defects in TiO2-δ:V thin films. The origin of room temperature ferromagnetism in these systems is discussed. Besides, the recent research findings in ZnO-based magnetic semiconductors are briefly discussed with focus on defect-induced ferromagnetism.

Keywords: Dilute magnetic oxides; Dilute magnetic semiconductors; Above room temperature ferromagnetism; Defect-induced ferromagnetism; Positron annihilation spectroscopy

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    Zhukov, A.: Novel Functional Magnetic Materials. Fundamentals and Applications. Springer Series in Materials Science 231, Switzerland: Springer International Publishing, 2016, 978-3-319-26104-1, 187-219
    DOI: 10.1007/978-3-319-26106-5_5
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