High magnetic field study of charge melting inBi1/2(Sr,Ca)1/2MnO3perovskites: Unconventional behavior of bismuth charge ordered compounds

Abstract

The stability of charge ordered phases of bismuth based ${\mathrm{Bi}}_{0.5}{\mathrm{Ca}}_{0.5}{\mathrm{MnO}}_{3}$ and ${\mathrm{Bi}}_{0.5}{\mathrm{Sr}}_{0.5}{\mathrm{MnO}}_{3}$ oxides is investigated by magnetization measurements in magnetic fields up to 130 T. Marked differences exist when comparing the critical fields ${\ensuremath{\mu}}_{0}{H}_{C}$ found to induce a ferromagnetic state in ${\mathrm{Bi}}_{0.5}{\mathrm{M}}_{0.5}{\mathrm{MnO}}_{3}$ (M=Ca, Sr) and ${\mathrm{Ln}}_{0.5}{\mathrm{Ca}}_{0.5}{\mathrm{MnO}}_{3}$ (Ln-rare-earth) manganites. Bi oxides do not match the general ${\ensuremath{\mu}}_{0}{H}_{C}\ensuremath{-}\ensuremath{\theta}$ or ${\ensuremath{\mu}}_{0}{H}_{C}\ensuremath{-}{T}_{\mathrm{CO}}$ monotonous tendencies showed by the half-doped manganites having rare earths. From this comparison, we suggest the possibility that, at least in the case of ${\mathrm{Bi}}_{0.5}{\mathrm{Sr}}_{0.5}{\mathrm{MnO}}_{3},$ the high-field ferromagnetic phase below $130\mathrm{T}$ could be insulating in nature.