Experimental studies of spin reorientations inEr2−xThxFe14B

Abstract

Er2−xThxFe14B (x = 0.0, 0.5, 1.0, 1.5, 2.0) polycrystalline compounds have been studied with57Fe Mössbauer spectroscopy, differential scanning calorimetry (DSC), magnetic measurements andx-ray diffraction. Special emphasis was put on the spin reorientation phenomena (change ofspin orientation from planar to axial arrangement) occurring in this series when increasingtemperature. The spin reorientation in each compound has been investigated mainly bynarrow step temperature scanning in the vicinity of the spin reorientation temperature,TSR.Initial magnetization versus temperature measurements allowed us to establish thetemperature regions of reorientations and the Curie temperatures of the compounds. Thetwo-stage character of transitions was evidenced.Mössbauer temperature scanning was performed with a step of 2 K in the vicinity ofTSR. The obtained spectra were analysed by using a procedure of simultaneousfitting and the transmission integral approach. Consistent fits were obtained;TSR and the composition dependences of hyperfine interaction parameters were derived from fitsfor all studied compounds.DSC studies proved that the spin reorientations were accompanied by thermal effects for compositionx = 0.5. Transformationenthalpy and TSR were determined from these studies and the two-stage character of the transition wasconfirmed.The TSR obtained with different methods were compared and the spin phase diagram for the serieswas constructed.