Crystal Growth and Characterization of the Rare-earth Orthoferrite Sm0.8Tb0.2FeO3 Single Crystal

Sm0.8Tb0.2FeO3 single crystal was grown by the floating zone method. Laue back reflection was used to check the crystal's quality and orientation. The temperature dependence of the magnetization under ZFC process was measured in an external field 500 Oe along c-axis. A clear spin reorientation is observed in the range of 360-400 K. Considering the recent report that the spin reorientation transition temperature of Sm1-xTbxFeO3 is linear decreased with the increase of Tb ions content, the present data reveals the changed Fe3+-Re3+ super-exchange interaction. The curve of temperature dependence of thermal expansion exhibits three phase transitions at about 250 K, 350-480 K, and 700 K, respectively. The abnormal phase transition observed at 250 K may be resulted from the change of rare earth ions moment orientation polarized by Fe3+ sub-lattice net moment. The spin reorientation transition takes place in a temperature range from 350 K to 480 K. The iron spins transform from antiferromagnetic ordered arrangement to paramagnetic disordered arrangement at similar to 700 K.