Neutron diffraction studies of the magnetic structures of HoAuGe and ErAuGe

The magnetic structures of HoAuGe and ErAuGe, both crystallizing in the hex agonal LiGeGa-type structure, have been investigated by high resolution neu tron diffractometry in the temperature range between 1.5 and 7.7 K. For ErA uGe, additional low temperature diffraction experiments have been performed between 40 mK and 1.4 K. Both compounds order antiferromagnetically at low temperatures. The magnetic structure of HoAuGe at 1.5 K is described by a propagation vector k = [1/2, 0, 0]. The low temperature diffraction pattern of ErAuGe is similar to that obtained for HoAuGe. however, some magnetic r eflections of ErAuGe show a significant broadening. This broadening is due to a magnetic domain size effect. Transversal sine wave incommensurate magn etic structures appear close to the Neel temperatures. These structures can be described by a propagation vector k = [0,4461(5), 0, 0] at 4.5 K for Ho AuGe and k = [0.4185(40),0, 0 ] at 3.0 K for ErAuGe. (C) 2001 Elsevier Scie nce B.V. All rights reserved.