MAGNETIC-STRUCTURES OF ERBIUM UNDER HIGH-PRESSURE

Neutron diffraction studies of the magnetic structures of erbium metal at 4.5 K and 11.5 kbar hydrostatic pressure have revealed that the transition to a conical structure at low temperatures is suppressed and that the cycloidal structure, with modulation vector Q congruent-to (2/7 2pi/c)c persists down to 4.5 K. The existence of higher-harmonic magnetic satellites indicates that the cycloid is squared up. Preliminary data at higher temperatures show that the cycloidal structure changes to a longitudinally modulated structure at approximately 50 K and that the modulation vector remains unchanged between 4.5 K and approximately 50 K, where it tends to increase. The intensities of the magnetic satellites originating from higher-order harmonics of the c-axis-moment component observed at 4.5 K decrease slowly with increasing temperature, but persist up to approximately 60 K.