Magnetic Susceptibility and Spin Exchange Interactions of the Hexagonal PerovskiteType Oxides Sr4/3(Mn2/3Ni1/3)O3

Magnetic susceptibility measurements were carried out for two hexagonal perovskite-type oxides Sr1+x(Mn1-xNix)O3 with slightly different compositions (i.e., x= and 0.324). A significant difference in the susceptibilities of the two phases demonstrates the need to control phase compositions accurately. Sr4/3(Mn2/3Ni1/3)O3 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 Sr4/3(Mn2/3Ni1/3)O3 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.