The effect of Ru substitution for Ti on the ground-state properties of three-dimensional antiferromagnet (AF) CaCu3 Ti4 O12 is studied by means of magnetic susceptibility and heat-capacity measurements. A small amount of Ru substituted for Ti suppresses AF long-range order and induces a new intermediate state with T2 -proportional heat capacity, which shows a clear contrast to a simple spin-dilution effect demonstrated by the Zn substitution for Cu. Ru substitution also creates a finite density of state at the Fermi level while keeping nominal valence of Cu ions to be 2+, which is essential to a novel insulator-to-metal crossover driven by an isovalent substitution of Ru4+ for Ti4+.
|ジャーナル||Physical Review B - Condensed Matter and Materials Physics|
|出版ステータス||Published - 2009 2 26|
ASJC Scopus subject areas