Determination of the magnetic structures in orthoferrite CeFeO3by neutron powder diffraction: first order spin reorientation and appearance of an ordered Ce-moment.

High resolution and high intensity neutron powder diffraction are used to determine the temperature dependence of the crystallographic and magnetic structure of the orthoferrite CeFeO3. The high temperatureGx-type magnetic coupling of the Fe-sublattice described by the Γ4(GxAyFz) irreducible representation changes at the spin reorientation temperatureTSR= 228 K to aGy-type coupling of Γ1(AxGyCz). The spin reorientation is of first order and sees a hysteresis of about 2.5 K atTSR. Below 35 K faint magnetic peaks reflectingCztype magnetic coupling appear and are argued to be related to the Ce-sublattice. Magnetic moments at 2 K amount toμFe= 4.15 μBandμCe= 0.11 μB. CeFeO3is only the secondRFeO3compound after DyFeO3showing this ground state magnetic structure of the Fe-sublattice. The orthorhombic structurePbnmis kept over the whole temperature range.