Magnetization of La- and Ce-doped CaMnO$_3$ manganite single crystals in a strong magnetic field

Studies of the magnetization curves of electron-doped single-crystal manganites Ca$_{1-x}$Ln$_x$MnO$_3$ (Ln–La$^{3+}$, Ce$^{4+}$, $x\le$ 0.12) in strong pulsed magnetic fields of up to 350 kOe have revealed a metamagnetic transition in Ca$_{0.9}$Ce$_{0.1}$MnO$_3$ in the temperature range 77–190 K. The critical transition fields increase to $\sim$350 kOe with the temperature decreasing to 100 K. The spin polarization is $\sim$50% of the theoretical value. These results are interpreted as due to “melting” of the orbital/charge ordering below the temperature $T_{\mathrm{OO/CO}}$ = 185 $K = T_N$ (of the C type AFM phase); this entails a decrease in the volume of the ordered phase with localized carriers and an increase in the volume of the ferromagnetic phase with delocalized carriers. The temperature and field dependences of the magnetization are used to compare two manganite systems in the region of the two-phase magnetic state.