INVESTIGATION OF THE HELIMAGNETIC PHASES OF HOLMIUM IN A C-AXIS MAGNETIC-FIELD

Neutron diffraction measurements have been made in the (hOl) plane of holmium in a c-axis magnetic field of 3 T. Thermal expansivity measurements have also been made by capacitance dilatometry. The main focus of our investigation has been a region about 2 K wide near 96 K, where the helimagnetic structure locks into a commensurate state. We have also been able to observe the "2-tau" satellites (at twice the fundamental magnetic ordering q vector) at temperatures as high as 3 K below the Neel transition. In the region between the lock-in transition and the Neel point, the intensities of these satellites show interesting behavior with temperature and may be showing effects due to the anomalies which have been identified in our magnetization measurements.