Journal of the Korean Physical Society

Korean Physical Society (한국물리학회)
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Ferromagnetic Properties of Ni-Doped Rutile $TiO_{2-\delta}$

Park, Young-Ran;Choi, Seung-li;Lee, Jung-Han;Kim, Kwang-Joo;Kim, Chul-Sung

  • Published : 20070300
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Abstract

Ni-doped rutile TiO$_{2-\delta}$ thin films grown by using the sol-gel method exhibited ferromagnetic and semiconducting properties at room temperature. The ferromagnetic strength of the TiO$_{2-\delta}$:Ni films was found to vary with Ni doping ($x$). The Ni-doped films had $p$-type electrical conductivity for small $x$ ($\le$5 at.\%) with the hole density increasing with $x$ while the undoped ones had $n$-type conductivity. Formation of Ni clusters was detected for large $x$ ($\ge$6 at.\%) by using X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and Hall effect measurements. The Ni ions in TiO$_{2-\delta}$:Ni were found to have valences of +2 and +3 by using XPS, with the latter having a larger density. The room-temperature ferromagnetism for $x$ $\le$ 5 at.\% is not attributable to mobile holes but to magnetic polarons formed around electrons trapped in oxygen vacancies.

Keywords

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