title: 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 AO(2) in which the cation A(4+) is substituted by a non-magnetic element of the 1 A column. Our purpose is to address experimentally the possibility of magnetism in Ti(1-x)K(x)O(2) compounds. The samples have been synthesized via the solid state route method at equilibrium. Our study has shown that Ti(1-x)K(x)O(2) is thermodynamically unstable and leads to a phase separation, in contradiction with the hypothesis of ab initio calculations. In particular, the crystalline TiO(2) grains appear to be surrounded by K-based phase. The oxidization state of the Ti ion is found to be in Ti(4+) as confirmed from the x-ray photoelectron spectra measurement. Nevertheless, K:TiO(2) compounds exhibit weak paramagnetism with the highest magnetic moment of ~0.5 μ(B) K(-1) but no long-range ferromagnetic order. The observed moment in these compounds remains much smaller than the predicted moment of 3 μ(B) by ab initio calculation. The apparent contradictions between our experiments and first-principles studies are discussed.
authors: Institut Néel, CNRS Grenoble and Université Joseph Fourier, 38042 Grenoble, Cedex 9, France.
authors: S K
authors: SK
authors: Srivastava
authors: P
authors: P
authors: Lejay
authors: B
authors: B
authors: Barbara
authors: O
authors: O
authors: Boisron
authors: S
authors: S
authors: Pailhès
authors: G
authors: G
authors: Bouzerar