Singlet ground state and magnetization plateaus in Ba3Mn2O8

Magnetic susceptibility and the magnetization process have been measured in Ba3Mn2O8 polycrystal. In this compound the magnetic manganese ion exists as Mn5+ in a tetrahedral environment, and thus the magnetic interaction can be described by an S = 1 Heisenberg model. The ground state was found to be a spin singlet with an excitation gal. Delta /k(B) = 11.2K. Magnetization plateaus were observed at zero and at half of the saturation magnetization. These results indicate that the present system can be represented by a coupled antiferromagnetic tic dimer model.