Magnetic and structural characteristics of ErFeO3, TmFeO3, and YbFeO3 single crystals were studied over a wide temperature range. Magnetic measurements found that the spin-rotation transitions in all crystals are well described by the earlier proposed theory with no fitting parameters. Additionally, they have shown the absence of the magnetic compensation point in TmFeO3 and a noticeable growth of the c-axis magnetization at low temperatures in TmFeO3 and ErFeO3. The x-ray measurements found no symmetry-lowering lattice distortions during the reorientation. Overall, the measurements cover a wide range of material parameters and demonstrate the generality of the modified mean field theory of the Γ4→Γ24→Γ2 orientation phase transitions in orthoferrites.

The results of magnetic measurements and x-ray analysis of the Mn0.89Cr0.11NiGe alloy are presented. It is shown that the temperatures of the first-order paramagnetic structural transition from hexagonal to orthorhombic phase and paramagnetic–ferromagnetic magnetic phase transition in the orthorhombic phase can be aligned by quenching the sample. This alignment results in the change of the magnetic phase transformation order: the initially isostructural phase transition of the second order becomes a magnetostructural transition of the first order (hexagonal paramagnet–orthorhombic ferromagnet). Moreover, the character of the low-temperature ferromagnetic–antiferromagnetic transition observed in magnetic fields below 3.5 T does not change substantially. The mechanisms of the giant anisotropic magnetostrictive (up to 10%) and magnetocaloric (up to 28 J/(kg·K) upon changing the magnetic field from 0 to 5 T) effects are discussed.

A giant softening by 30 cm −1 of the 490 and 620 cm −1 Jahn-Teller and breathing optical phonon modes is observed in Raman spectroscopy below the Curie temperature of single crystalline LaMnO 3+␦ ͑0.085ഛ ␦ ഛ 0.125͒. A pseudogaplike suppression of a continuum and a Fano antiresonance at 144 cm −1 appear below the charge-ordering temperature. Upon going through the antiferromagnetic/ferromagnetic insulating phase boundary a high-frequency maximum of three-peaks structure evolves to a unstructured, broadened maximum while undergoing a softening in the peak energy. This is interpreted in terms of the presence of fluctuating orbitals and mobile holes which form a stripelike state in the lightly doped, insulating manganites.

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