Hexagonal orthoferrites of rare earths RFeO3 (R = Lu, Er-Tb) were grown epitaxially on (111)ZrO2(Y2O3) substrates using metal-organic chemical vapour deposition. Temperature and field dependences of magnetization were measured and analyzed for all samples and revealed weak ferromagnetic behavior below T = 120–140 K. The difference in electronic structure along with a distinct similarity in the crystal structure of hexagonal manganites RMnO3 and hexagonal orthoferrites RFeO3 are brought into focus in order to explain the results. Hexagonal orthoferrites are regarded as a promising family of multiferroics.

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PACS. 75.30.Vn Colossal magnetoresistance – 61.12.Ld Single-crystal and powder diffraction,

The magnetic structure of the series (La 1Ϫy Pr y ) 0.7 Ca 0.3 MnO 3 for y from 0.5 to 1.0 has been studied by neutron powder diffraction in the temperature range from 10 to 293 K and in external magnetic fields up to 4 T. The phase diagram has a border region of concentrations 0.6рyр0.8 separating the homogeneous ferromagnetic ͑FM͒ metallic and canted antiferromagnetic ͑AFM͒ insulating states. In this region the lowtemperature magnetic state is macroscopically (Ͼ10 3 Å) separated into AFM and FM phases. The FM phase has a small noncollinearity, presumably due to interfaces to the AFM phase. The macroscopical clusters can be induced by disorder on the carrier's hopping amplitude caused by natural dispersion of the A cation radius near the metal-insulator transition around yϭ0.7. For the concentrations yу0.9 the long-range ordered magnetic state is homogeneous with a canted AFM structure. The total long-range ordered magnetic moment of the Mn ion shows a steplike decrease from Mn ϭ3.4 B to 2.5 B as a function of Pr concentration at the transition to a homogeneous canted antiferromagnetic ͑CAF͒ state. The spatial inhomogeneities can still be present for y у0.9, according to the reduced Mn value, but the Mn spins between the homogeneously CAF-ordered moments have to be either short-range ordered or paramagnetic. In addition, a ferromagnetic contribution of the Pr moments parallel to the ferromagnetic component of Mn moments is found for yϾ0.6. The moment of Pr scales with the ferromagnetic Mn moment rather than with the Pr concentration and thus presumably induced by Mn.

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