Magnetic structure and spin reorientation transitions in a system of manganese-substituted thulium orthoferrites

Abstract

Results of magnetic measurements carried out on single crystals of TmFe1-xMnxO3 (x=0, 0.12, 0.21 and 0.33) at temperatures in the region 2-700K and neutron diffraction investigations performed on powder samples at temperatures 80-650K are presented. The compounds are weak ferromagnets at room temperature. For compounds with a lower amount of manganese (x=0.12 and x=0.21) the spin reorientation phase transition GxFz-GzFx is observed as was already reported for pure TmFeO3(x=0). For the compound with x=0.33 a phase transitions sequence unusual for the pure orthoferrites is established. On the temperature dependence of the spontaneous magnetisation along the crystal a axis a compensation point was observed in the case of all compounds investigated. A qualitative explanation of the experimental results is given on the basis of recent theoretical considerations about the influence of Mn3+ doping ions on rare earth orthoferrite properties.