Using resonant x-ray scattering to perform diffraction experiments at the U M4 edge novel reflections of the generic form <kkk> have been observed in UAs0.8Se0.2 where k=<k00>, with k=1/2 reciprocal lattice units, is the wave vector of the primary (magnetic) order parameter. The <kkk> reflections, with 10−4 of the <k00> magnetic intensities, cannot be explained on the basis of the primary order parameter within standard scattering theory. A full experimental characterisation of these reflections is presented including their energy, azimuthal and temperature dependencies. On this basis we establish that the reflections most likely arise from the electric dipole operator involving transitions between the core 3d and partially filled 5f states. The temperature dependence couples the <kkk> peak to the triple-k region of the phase diagram: Below ∼50 K, where previous studies have suggested a transition to a double-k state, the intensity of the <kkk> is dramatically reduced. Whilst we are unable to give a definite explanation of how these novel reflections appear, this paper concludes with a discussion of possible ideas for these reflections in terms of the coherent superposition of the 3 primary (magnetic) order parameters.
@article{arxiv.cond-mat/0309012,
title = {Multi-$\vec{k}$ Configurations},
author = {N. Bernhoeft and J. A. Paixão and C. Detlefs and S. B. Wilkins and P. Javorsky and E. Blackburn and G. H. Lander},
journal= {arXiv preprint arXiv:cond-mat/0309012},
year = {2016}
}