Magnetic, electric and electron magnetic resonance properties of orthorhombic self-doped La1-xMnO3 single crystals

The effect of lanthanum deficiency on structural, magnetic, transport, and electron magnetic resonance (EMR) properties has been studied in a series of La1-xMnO3 (x = 0.01, 0.05, 0.11, 0.13) single crystals. The x-ray diffraction study results for the crystals were found to be compatible with a single phase of orthorhombic symmetry. The magnetization curves exhibit weak ferromagnetism for all samples,below 138 K. It was found that both the spontaneous magnetization and the coercive field increase linearly with x. The pressure coefficient dT(N)/dP decreases linearly with self-doping, from a value of 0.68 K kbar(-1) for La0.99MnO3 to 0.33 K kbar(-1) for La0.87MnO3. The resistivity of low-doped La0.99MnO3 crystal is of semiconducting character, while that of La0.87MnO3 depends weakly on temperature between 180 and 210 K. It Was found that the magnetic and transport properties of the self-doped compounds may be attributed to a phase separation involving an antiferromagnetic matrix and ferromagnetic clusters. The latter phases as well as their paramagnetic precursors have been directly observed by means of EMR.