Antiferromagnetic Order in Disorder-Induced Insulating Phase of   SrRu_{1-x}Mn_xO_3 (0.4<x<0.6)
  We have performed the powder neutron diffraction measurements on the solid solutions of SrRu_{1-x}Mn_xO_3, and found that the itinerant ferromagnetic order observed in pure SrRuO_3 changes into the C-type antiferromagnetic (AF) order with nearly localized d electrons in the intermediate Mn concentration between x=0.4 and 0.6. With increasing x, the AF moment is strongly enhanced from 1.1 mB (x=0.4) to 2.6 mB (x=0.6), which is accompanied by the elongation of the tetragonal c/a ratio. These results suggest that the substitution of Mn for Ru suppresses the itinerant character of the d electrons, and induces the superexchange interaction through the compression in the c plane. We have also found that the magnetic and transport properties observed in our tetragonal samples are quite similar to those of recently reported orthorhombic ones. 
M. Yokoyama, C. Satoh, A. Saitou, H. Kawanaka, H. Bando, K. Ohoyama   and Y. Nishihara