High pressure neutron diffraction studies of the magnetic structures of Tb, Ho and Er

Pressure effects of the magnetic structures of Tb, Ho and Er have been studied by neutron diffraction using a newly-developed clamp type pressure cell. For Tb the pressure dependence of the turn angle in a helical phase shows an enhancement of its value, particularly in low temperatures with increasing pressure but no lock-in feature. Linear coefficients of the magnetic transition temperatures to pressure are obtained. For Ho the turn angle is increased by pressure and shows an almost linear temperature dependence at high temperatures and lock-in features at low temperatures. For Er the high pressure results reveal that the transition to a conical structure at low temperatures is suppressed and that a cycloidal structure with a modulation vector Q = 2/7(2π/c) persists down to 4.5 K, similar to a three up four down structure in Tm. (author)