NEUTRON-DIFFRACTION AND TOPOGRAPHIC INVESTIGATION OF THE MULTIPHASE MAGNETIC TRANSITION IN MNRHAS

Clues to understanding the way the magnetic transition between two of the magnetically ordered phases (with propagation vectors [0,0,q(z)] where q(z) = 1/4 and q(z) = 1/2 occurs in MnRhAs are obtained by combining neutron diffraction and topography experiments. They show that at least four magnetic phases coexist in a 15 K range. This behaviour can be explained through a distribution of transition temperatures over the various areas of the crystal. The additional phases are characterized by a commensurate (q(z) = 1/6) and an incommensurate q(z)(T) components respectively. They are stable only in narrow temperature ranges. The interface orientations observed on the topographs is explained by means of elastic arguments. The origin of the observed q(z)(T) is discussed.