U(As1-xSex) solid solutions. I. Resonant x-ray and neutron scattering study of the magnetic phase diagram

We report on a study of the magnetic structure and phase transitions of the UAs_1-xSe_x solid solutions employing x-ray and neutron scattering. We have focused this study on compositions 0.18<x<0.22, in which magnetic structures having double-k and triple-k configurations are found with increasing x. In general, our findings are in excellent agreement with those reported by Kuznietz et al. using solely neutron diffraction. However, our x-ray studies have added several important details about (1) the incommensurate transitions near T_N, (2) the nature of the 2k-3k phase boundary, and (3) the discovery of a new magnetic phase.