Density-functional characterization of antiferromagnetism in oxygen-deficient anatase and rutile TiO2

Abstract

We present theoretical evidence for local magnetic moments on Ti 3+ ions in oxygen-deficient anatase and rutile TiO2 observed in a recent experiment. Results of our first-principles GGA+U calculations reveal that an oxygen vacancy converts two Ti4+ ions to two Ti3+ ions in anatase phase, which results in a local magnetic moment of 1.0 μB per Ti3+. The two Ti3+ ions, however, form a stable antiferromagnetic state, and similar antiferromagnetism is also observed in oxygen-deficient rutile phase TiO2. The calculated results are in good agreement with the experimentally observed antiferromagneticlike behavior in oxygen-deficient Ti-O systems. © 2010 The American Physical Society.