Antiferromagnetic metallic state in the heavily doped region of perovskite manganites

Abstract

Comprehensive study on electronic and magnetic properties has been performed for doped manganite near the phase boundary of the antiferromagnetic metallic (AFM) state, with changing the nominal hole concentration $x$ and the one-electron bandwidth $W$. In ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ with maximal $W,$ the ferromagnetic metallic ground state in the low-$x$ region is replaced by the AFM state beyond $x=0.54$. On the other hand, the charge-ordered insulating (COI) state appears at $x\ensuremath{\sim}0.5$ for ${\mathrm{Nd}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{x}$ with reduced $W.$ The COI ground state is overwhelmed by the AFM state with further increasing $x(>~0.54)$ or $W.$ These competitions of the AFM state with the alternative ground states suggest that the AFM state is a fundamental ground state for doped manganites.