Magnetostriction effects of 3d4 and 3d6 ions in dilute magnetic oxide films

Magnetic ions of the 3d(n) transition series in oxide lattices can introduce large local magnetostriction effects through spin-orbit-lattice interactions with an axially distorted cubic crystal field. In this paper, the local-site magnetostriction model used successfully in ferrites containing small concentrations of Jahn-Teller (JT) ions is applied to the case of magnetically dilute oxide films. Uniaxial anisotropy created by elastic lifting of the orbital E(g) ground-state doublet degeneracy of 2% Cr(2+)(3d(4)) in an In(2)O(3) film is contrasted with the corresponding effects of a T(2g) triplet splitting of 5% Co(3+)(3d(6)) in a Si/SiO(2) film deposited under similar in-plane stress conditions. In these two situations, the signs of the magnetostrictive strains are reversed as predicted from theory and are consistent with local magnetoelastic effects of JT ions in undiluted ferrites. A phenomenological analysis of room-temperature magnetization data suggests a possible magnetostriction constant range of 0.02 < 0.2 for a single JT octahedral site. (C) 2008 American Institute of Physics.