Charge ordering in Sm4Bi3 under pressure

We have investigated the charge ordering in Sm4Bi3 under pressure by magnetic susceptibility and x-ray diffraction measurements. We observed discontinuous anomalies in the temperature dependences of magnetic susceptibility and volume at the charge ordering transition owing to the first-order transition and then the estimated charge ordering transition temperature decreases linearly with increasing pressure. The volume ratio between the SmBi6 octahedra at two nonequivalent Sm sites indicates the partial charge ordering of Sm ions in the charge ordered phase. The evidence of the partial charge ordering in Sm4Bi3 is consistent with the smaller electronic component in the entropy change at the charge ordering transition.