Absence of ferromagnetism in electron-doped rare-earth manganates, Ln1−xAxMnO3 (x>0.5)

In order to explore whether the ferromagnetic metallic state ever occurs in the electron-doped rare-earth manganates, a comparative study of the effects of magnetic fields and of cation substitution in the Mn-site were carried out on hole-doped Pr0.64Ca0.36MnO3 and electron-doped Pr0.36Ca0.64MnO3. Unlike Pr0.64Ca0.36MnO3, which attains a ferromagnetic metallic state under an applied magnetic field or on 3% Ru (Cr3+) doping in the Mn-site, Pr0.36Ca0.64MnO3 failed to exhibit ferromagnetism even on applying magnetic field on a Ru-doped sample. A study of La0.33Ca0.33Sr0.34MnO3 with a larger Mn–O–Mn angle has shown it to be a paramagnetic insulator. This manganate also does not exhibit ferromagnetism on 3% Ru substitution and/or on application of a 12T magnetic field. The present study establishes the absence of ferromagnetism in electron-doped manganates under all conditions.