Electronic phase diagram and phase separation in Cr-doped manganites

Magnetic properties are systematically investigated for Cr-doped manganites $R_{1/2}{\mathrm{Ca}}_{1/2}(\mathrm{M}\mathrm{n},\mathrm{C}\mathrm{r}){\mathrm{O}}_3$ $(R=\mathrm{La},$ Nd, Sm, and Eu) with variation of the averaged ionic radius $r_R$ of the rare-earth ion, or the one-electron bandwidth W. Cr-doping procedure on the perovskite B site significantly unstabilizes the charge-ordered (CO) state, and induces the ferromagnetic metallic (FM) state in the large-$r_R(>~1.29\hspace{0.5em}\AA )$ region. We have found coexistence of the CO domains in the FM phase, or the electronic phase separation, near the FM-CO phase boundary.