4d electronic and magnetic characteristics in postperovskite CaRuO3

The magnetic and electronic properties of postperovskite CaRuO3 are investigated by performing the first-principles calculation based on generalized gradient approximation plus parameter U method. A Mott-Hubbard insulating ground state with low spin Ru4+ is found, and the A-type antiferromagnetic (AFM) spin ordering is preferred. Ru4+ ions exhibit the spatially anisotropic exchange with the exchange in a-b plane weaker than that along c direction. The large Jahn-Teller distortion lowers the energy of d(z)2 orbital, leading to the stabilization of low spin Ru4+ and ferromagnetic (FM) orbital ordering. The transitions of metal-insulator and FM-AFM-FM depend on the Hubbard parameter U. (C) 2010 American Institute of Physics. [doi:10.1063/1.3360344]