Neutron Diffraction Study of the p - T Phase Diagram for Erbium

Abstract

Electrical resistivity measurements performed on a single crystal of erbium as a function of temperature and hydrostatic pressure have provided a preliminary p-T phase diagram. The results have been interpreted in terms of a model for the magnetic structures of Er deduced from neutron diffraction studies at ambient pressure. This model predicted the existence of a magnetic structure with a wave vector of Q ¼ 2=7 c* at 4.2 K, when the applied pressure is larger than 3 kbar. This paper reports a neutron diffraction study of erbium made in the temperature range of 4 to 100 K, at pressures between 0.5 and 6 kbar. We have observed the predicted suppression of the low temperature conical ferromagnetic phase and the emergence of a new phase with Q ¼ 8=33 c*. The neutron diffraction measurements has enabled us to identify the various phases that develop from the cycloidal phases previously observed at atmospheric pressure.

Magnetic and structural phase transitions in erbium at low temperatures and high pressures

“…Neutron diffraction studies of the magnetic structure by Kawano, et al [15,16] found at 1.15 and 1.4 GPa pressure that the transition to the ferromagnetic conical structure is completely suppressed with the elliptical cycloidal structure persisting down to 4.5 K. The CAM antiferromagnetic ordering decreased from 84 K at ambient pressure to 82 K at 1.4 GPa pressure while the cycloidal structure at 1.4 GPa was initially observable at 46 K. The suppression of the low-temperature ferromagnetic conical structure under pressure was confirmed by another neutron diffraction study [17] at 6.0 K which suggested at pressures as low as 0.5 GPa that the conical phase is destroyed. Other studies of the pressure-vs.-temperature phase diagrams are based on a very limited number of pressure-dependent resistivity and magnetic susceptibility measurements.…”