Room temperature ferromagnetism in transition metal (V, Cr, Ti) doped In₂O₃

Abstract

Indium oxide is chosen as the host material for doping Ti, V, and Cr transition metal ions. Theoretical calculations based on density functional theory within a local spin density approximation show that V-V separation of 5.6 Å is more stable with a strong ferromagnetic coupling. Our calculations clearly predict that substitution of vanadium for indium should yield ferromagnetism in In₂O₃. Experimentally, (In_0.95TM_0.05)O₃ (TM = Ti,V,Cr) were prepared using sol-gel as well as solid state reaction methods. Superconducting quantum interference device magnetization measurements as a function of field and temperature clearly showed that the V and Cr doped samples are ferromagnetic with Curie temperature well above room temperature. Thin films deposited by pulsed laser ablation using these materials on sapphire substrates exhibit a preferred 222 orientation normal to the plane of the film. The magnetic moment for (In_0.95V_0.05)O₃ film deposited in 0.1 mbar oxygen pressure was estimated to be 1.7μ_B/V and is comparable to the theoretical value of 2μ_B/V.