Neutron diffraction and electrical transport studies on magnetic ordering in terbium at high pressures and low temperatures

Abstract

Neutron diffraction and electrical transport measurements have been carried out on the heavy rare-earth metal terbium at high pressures and low temperatures in order to elucidate the onset of ferromagnetic (FM) order as a function of pressure. The electrical resistance measurements show a change in slope as the temperature is lowered through the FM Curie temperature. The temperature of this FM transition decreases at a rate of−16.7 K/GPa up to a pressure of 3.6 GPa, at which point the onset of FM order is suppressed. The neutron diffraction measurements as a function of pressure at temperatures ranging from 90 to 290 K confirm that the change of slope in the resistance is associated with the FM ordering, since this occurs at pressures similar to those determined from the resistance results at these temperatures. A disappearance of FM ordering was observed as the pressure is increased above 3.6 GPa and is correlated with the phase transition from the ambient hexagonal close packed structure to an α-Sm-type structure at high pressures.

Keywords:

• neutron diffraction
• electrical transport
• rare-earth metals
• magnetism
• high pressures–low temperatures

Acknowledgements

This material is based upon the work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0002014. Sarah A. Thomas acknowledges support from the NASA-Alabama Space Grant Consortium Graduate Fellowship program under NNX10AJ80H. Jeffery M Montgomery acknowledges the support from the Department of Education Grant No. P200A090143. A portion of this research at Oak Ridge National Laboratory's Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy.