We report a systematic study of spin and charge ordering in cubic perovskites ${\mathrm{Ba}}_{1-x}{\mathrm{La}}_x{\mathrm{FeO}}_3$ ($0.1\le x\le 0.5$) obtained by high-pressure syntheses. On the basis of detailed magnetic measurements including Mössbauer spectroscopy, a previously unreported spin-charge correlated phase is found to emerge around $x=0.2$ as an intermediate phase between the helimagnetic phase near $x=0$ and the commensurate spin-charge ordered phase around $x=1/3$. Mössbauer spectra measured at low temperatures reveal that the charge disproportionation, expressed as $2{\mathrm{Fe}}^{(4-x)+}\to (1+x){\mathrm{Fe}}^{3+}+(1-x){\mathrm{Fe}}^{5+}$, takes place over a wide range of the helimagnetic phase, from around $x=1/3$ down to 0.1, where long-range ordering of charge disproportionation is disturbed presumably by the incommensurate helimagnetic order. This work reveals strong charge disproportionation instability potentially coupling with helical spin ordering in ${\mathrm{Fe}}^{4+}$-based perovskite oxides.

Close

PrevNext

View figure in article

• Charge order
• Magnetic order
• Strongly correlated systems
• Transition metal oxides
• Mössbauer spectroscopy