On the helical-paramagnetic phase transition and a possible vortex state in dysprosium

Abstract
A high-resolution neutron-diffraction investigation of the planar helical-paramagnetic phase transition in Dy observed the helical order parameter to be continuous both in the vicinity of T2 approximately=171K where Amitin et al. (1984) observed a c-axis strain discontinuity and at the Neel temperature where a recent renormalisation group calculation predicts a first-order transition.