Magnetic susceptibility and spin exchange interactions of the hexagonal perovskite-type oxides Sr4/3(Mn2/3Ni1/3)O3

Magnetic susceptibility measurements were carried out for two hexagonal perovskite-type oxides Sr1+x(Mn1-xNix)O-3 with slightly different compositions (i.e., x = 1/3 and 0.324). A significant difference in the susceptibilities of the two phases demonstrates the need to control phase compositions accurately. Sr-4/3(Mn2/3Ni1/3)O-3 consists of two spin sublattices, i.e., the Mn4+ and the Ni2+ ion sublattices. Spin dimer analysis was carried out to examine the relative strengths in the spin exchange interactions of the Mn4+ ion sublattice. The temperature dependence of the magnetic susceptibility of Sr-4/3(Mn2/3Ni1/3)O-3 was found consistent with a picture in which the Mn4+ ion sublattice has weakly interacting antiferromagnetically coupled (Mn4+)(2) dimers, the Ni2+ ion sublattice acts as a paramagnetic system, and the two sublattices are nearly independent. (C) 2002 Elsevier Science.