Anomalous behavior of the thermopower and temperature derivative of resistivity near the spin reorientation transition in Er2Fe14B

Abstract

Experimental observation of the first-order nature of the spin reorientation transition in polycrystalline Er2Fe14B through high resolution resistivity, thermopower and Fe57 Mössbauer data is reported. Both a steplike decrease in resistivity and an increase in thermopower over a very narrow temperature interval around 323 K indicate a discontinuous spin reorientation transition. This is consistent with the change in sign of the quadrupolar shifts at all Fe sites at this temperature, derived from the Mössbauer spectra, which are indicative for the transition from planar to uniaxial anisotropy with increasing temperature. The symmetrical lineshape of the sharp singularity recorded in the temperature derivative of resistivity provides unambiguous evidence for the first-order nature of the spin reorientation.