Magnetic Study of the Ca1−xEuxMnO3(0≤x≤1) Perovskites

Bulk modulus and thermodynamic properties of electron-doped calcium manganate—Ca1−xRExMnO3

“…This difference was ascribed to orbitally degenerate e g levels of slightly electron-doped CaMnO 3. It was also observed in Ca 1Àx A x MnO 3 (A ¼ Pr, Nd, Eu, Gd, Ho, Ce, Th), a large magnetoresistance appears in a very narrow range of carrier concentration with unusual effects of the variation of the average size of the ions at the rare earth site [5]. Similar study of the manganite Ca 1Àx Eu x MnO 3 for xo0.2 [6] showed that the electron doping due to the substitution of the trivalent rare earth Eu(III) for calcium induces a magnetoresistance effect with small resistivity ratio i.e., R 0 /R 12T ¼ 4 at 30 K. These results are quite unexpected if one takes into account the average size of the interpolated cations at the A-site which is small compared to the one required for the appearance of the CMR effect in hole-doped manganites.…”

“…where average tilting of the BO6 octahedral around pseudocubic direction [111] is /oS and /yS is the average super-exchange angle Mn-O-Mn. Experimentally it was observed that super-exchange angle Mn-O-Mn increases towards 1801 with increasing external pressure and similar effect can be observed by increasing the average cation size at the A-site (substitution with larger rare earth ion) in CaMnO 3 .…”

Ferromagnetic polarons in manganites

“…It can be seen that the localization of the polaron decreases with magnetic field as a consequence of increased effective hopping between nearest neighbors. A fact that may be important for the transport properties of these systems since it implies a negative magnetoresistive behavior for conductivity due to hopping between localized states [35,14,15]. The size of the magnetic distortion relative to the background increases with the magnetic field (see Fig.6(b)).…”

Effects of nonstoichiometry on the properties of electron-doped manganite Pr0.1Ca0.9MnO3

“…Among the interesting phenomena, colossal magnetoresistance (CMR) effect is of great importance because of its potential applications in the electronic industry. Different from the hole-doped side, CMR is observed only in a narrow range of compositions for electron-doped manganites [1][2][3], as indicated by the phase diagram of Pr 1Àx Ca x MnO 3 [4]. It is noteworthy that the physical properties of the Pr 1Àx Ca x MnO 3 system are sensitive to the concentration of charge carrier near x ¼ 0.9, where a transition from antiferromagnetic insulating state, concomitant with charge ordering to cluster glass, occurs, and the CMR effect is observed as well.…”