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We have presented the structural, surface morphology, magnetic and resistivity data for perovskite LaMnO3 epitaxial thin films which are fabricated on well-oriented (001) LaAlO3 substrates by pulsed laser deposition technique. X-ray diffraction [Formula: see text]–[Formula: see text] linear scans and reciprocal space mapping measurement confirm that the out-of-plane and in-plane epitaxial relationship are LMO(001)/LAO(001) and LMO(110)/LAO(110), respectively. Surface roughness determined by atomic force microscopy was no more than 0.3 nm. In the whole studied temperature range, all films only show a paramagnetic behavior instead of any magnetic phase transitions. Correspondingly, the electron transport behaviors always exhibit an insulting state as the temperature changes from high to low. However, we find that none of theoretical models can individually be used to understand their conductive mechanisms. Further studies indicated that charge carries of high and low temperature region obey adiabatic and nonadiabatic small polaronic hopping mechanisms, respectively. This finding offers new ways of exploiting the abnormal ferromagnetism in LaMnO3 multilayer thin films.

In this paper, we report the electron paramagnetic resonance (EPR) study of perovskite manganite Nd 0.55 Sr 0.45 MnO 3. Experimental data reveal that the EPR linewidth broadens with a quasilinear manner up to 480 K. The broadening of the EPR linewidth can be understood in terms of the shortening of carrier–lattice relaxation time due to the occurrence of strong carrier–phonon interactions. Two same activation energies obtained respectively from the temperature dependence of EPR intensity and resistivity indicate that the linewidth variation is correlated to the small polaron hopping. Therefore, the carrier–lattice coupling play a major role for deciding its magnetism in the present system.

In this paper, we have systematically investigated the thermomagnetic properties of SrRu 0.8 Fe 0.2 O 3. An exceptional large thermomagnetic irreversibility has been found in the measurement of magnetization with zero-field cooling and field cooling mode. Moreover, as one increases the applied magnetic field, the thermomagnetic irreversibility is further enlarged. Even though an obvious antiferromagnetic phase transition occurs in T = 50 K , the main reason for the thermomagnetic irreversibility derives from the field driven-antiferromagnetic–ferromagnetic transition in higher temperature region, where spin fluctuation induced by Fe -dopant shifts the pristine FM exchange into antiferromagnetic exchange interaction in Ru 4+– O 2-– Ru 4+ spin network.

Structural and magnetic properties of Bi0.5 Ca0.5-xBaxMnO3 (x = 0, 0.03, 0.05, 0.07 and 0.10) samples with charge ordering (CO) state and C-type antiferromagnetic (AFM) magnetic structure have been studied systematically. With increasing Ba-doping level, both CO and AFM are weakened. From the micro-magnetic analysis, we clarify the ambiguity about the Néel temperature TN in bismuth-based perovskite manganites. We find that the paramagnetic (PM)-CO/AFM transition temperature TCO at high temperature is the onset temperature of the PM–AFM transition, while customarily so-called TN at low temperature indicates the finish of the PM–AFM transition. Both the macro- and micro-magnetic data show that, in all the samples, only AFM state coexists with PM matrix below CO transition and above TN, while AFM state coexists with ferromagnetic (FM) state and PM state at lower temperature below TN.