Crystal and magnetic structure of CaRuO

Yoshida, Yoshiyuki*; Ikeda, Shinichi*; Matsuhata, Hirofumi*; Shirakawa, Naoki*; Lee, C.-H.*; Katano, Susumu

The crystal structure of the double-layered CaRuO has been studied by convergent beam electron diffraction and powder neutron diffraction. The temperature dependence of the diffraction pattern reveals that all the lattice constants jump at the first-order metal-nonmetal transition at 48 K without a change of the space group symmetry of Bb21m. In the neutron diffraction experiment, an additional magnetic reflection emerges below the Neel temperature, 56K. A possible model for this antiferromagnetic ordering is proposed, in which model magnetic moments align ferromagnetically within the double layer and antiferromagnetically between the double layers. This model reasonably explains the characteristic field dependence of the magnetoresistance observed at around 6 T.