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Journal Articles Journal of Physics: Condensed Matter Year : 2011

Non-magnetic impurity induced magnetism in rutile TiO2:K compounds

Abstract

Recent ab initio studies have theoretically predicted room temperature ferromagnetism in several oxide materials of the type AO2 in which the cation A4+ is substituted by a non-magnetic element of the 1 A column. Our purpose is to address experimentally the possibility of magnetism in Ti1−xKxO2 compounds. The samples have been synthesized via the solid state route method at equilibrium. Our study has shown that Ti1−xKxO2 is thermodynamically unstable and leads to a phase separation, in contradiction with the hypothesis of ab initio calculations. In particular, the crystalline TiO2 grains appear to be surrounded by K-based phase. The oxidization state of the Ti ion is found to be in Ti4+ as confirmed from the x-ray photoelectron spectra measurement. Nevertheless, K:TiO2 compounds exhibit weak paramagnetism with the highest magnetic moment of ~0.5 μB K−1 but no long-range ferromagnetic order. The observed moment in these compounds remains much smaller than the predicted moment of 3 μB by ab initio calculation. The apparent contradictions between our experiments and first-principles studies are discussed.
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Dates and versions

hal-01010635 , version 1 (20-06-2014)

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Sandeep Srivastava, Pascal Lejay, Bernard Barbara, O. Boisron, S. Pailhes, et al.. Non-magnetic impurity induced magnetism in rutile TiO2:K compounds. Journal of Physics: Condensed Matter, 2011, 23 (44), pp.442202. ⟨10.1088/0953-8984/23/44/442202⟩. ⟨hal-01010635⟩
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