%0 Journal Article
%A Kotla, Surya Rohith
%A Noohinejad, Leila
%A Pokhriyal, Preeti
%A Tolkiehn, Martin
%A AGARWAL, HARSHIT
%A Ramakrishnan, Sitaram
%A van Smaalen, Sander
%T Broken inversion symmetry in the charge density wave phase in EuAl<sub>4</sub>
%J Physical review / B
%V 112
%N 6
%@ 2469-9950
%C Woodbury, NY
%I Inst.
%M PUBDB-2025-03846
%P 064113
%D 2025
%X EuAl<sub>4</sub> exhibits a complex phase diagram, including the development of a charge density wave (CDW) below T<sub>CDW</sub> = 145K. Below T<sub>N</sub> = 15.4K, a series of antiferromagnetically (AFM) ordered phases appear, while nontrivial topological phases, like skyrmion lattices, are stabilized under an applied magnetic field. The symmetries of the variously ordered phases are a major issue concerning the understanding of the stabilization of the ordered phases as well as concerning the interplay between the various types of order. EuAl<sub>4</sub> at room temperature has tetragonal symmetry with space group I4/mmm. The CDW phase has an incommensurately modulated crystal structure described by the modulation wave vector q ≈ 0.17 c<sup>∗</sup>. On the basis of various experiments, including elastic and inelastic x-ray scattering, and second-harmonic generation, it has been proposed that the symmetry of the CDW phase of EuAl<sub>4</sub> could be centrosymmetric orthorhombic, noncentrosymmetric orthorhombic or noncentrosymmetric tetragonal. Here, we report temperature-dependent, single-crystal x-ray diffraction experiments that show that the CDW is a transverse CDW with phason disorder, and with noncentrosymmetric symmetry according to the orthorhombic superspace group F222(0 0 σ )00s. Essential for this finding is the availability of a sufficient number of second-order (2q) satellite reflections in the x-ray diffraction data set. The broken inversion symmetry implies that skyrmions might form due to Dzyaloshinskii-Moriya (DM) interactions, instead of a more exotic mechanism as it is required for centrosymmetric structures.
%F PUB:(DE-HGF)16
%9 Journal Article
%R 10.1103/kl2z-brms
%U https://bib-pubdb1.desy.de/record/637354