Antiferromagnetic metallic state in doped manganites

Electronic and magnetic properties are systematically investigated for doped manganites R_1-xSrₓMnO₃ (R=La_1-zNdz) by changing the nominal hole concentration x and the averaged ionic radius of the perovskite A site $(z),$ or the one-electron bandwidth $W.$ In the heavily doped region $(x>~0.50),$ we observed a layered-type (A-type) antiferromagnetic state with metallic conductivity (ρ≈4×10^-4Ωcm at 5 K for La0.46Sr0.54MnO₃). This observation suggests that the antiferromagnetic metallic (AFM) state is the alternative ground state for doped manganites, besides the ferromagnetic metallic (FM) state.