H-T magnetic phase diagrams of electron-doped Sm1-xCaxMnO3

The magnetic properties of the polycrystalline electron-doped manganites Sm 1-xCaxMnO3 have been studied for 1 greater than or equal to x greater than or equal to 0.67 under high magnetic fields up to 50T.H-T phase diagrams ha ve been established. Doping the G-type AFM parent compound CaMnO3 leads to partial FM correlations superimposed on a AFM component. The former phenome na reaches its maximum strength for x = 0.88-0.9. For x = 0.8 and below, ab rupt metamagnetic transitions occur from the AFM ground state to the FM sta te with large hysteresis between the first magnetization and remanence curv es. This phenomena corresponds to the melting of the orbital- or charge-ord ered phases. At intermediate concentrations close to x = 0.85, the magnetiz ation curves exhibit first a FM component and then a metamagnetic transitio n, so that this behavior can thus be viewed as a sum of the two types of pr evious behaviors, clearly showing the occurrence of phase separation. (C) 2 001 Elsevier Science B.V. All rights reserved.