High pressure effects on the crystal and magnetic structure of 160Gd metal

Abstract

Structural and magnetic properties of the isotopically substituted 160Gd metal (97.5 % enrichment) were studied by means of neutron powder diffraction at pressures up to 9 GPa in the temperature range 7 – 290 K. At ambient conditions, a coexistence of hexagonal close packed (hcp) and Sm-type rhombohedral phases was observed. Under high pressure, the hcp phase was suppressed gradually and above 6 GPa only the Sm-type phase is observed. The long range ferromagnetic order formed in the hcp phase is also suppressed rapidly with a pressure coefficient of the Curie temperature dTC/dP = -6.3(1) K/GPa. In the Sm-type phase below the Néel temperature of about 100 K (evaluated for 9 GPa), the long range antiferromagnetic order with a propagation vector kAF = (0 0 1/2) is formed. The lattice parameters and unit cell volume as functions of pressure in the hcp and Sm-type phases were determined. A partial phase transformation of the Sm-type phase to the double hexagonal close packed (dhcp) phase was observed at 9 GPa.