Evolution of Charge Order in Ba_1-xSr_xAl₄

The BaAl₄ type structure also hosts a variety of interesting and exotic properties. Recent results have shown an emergence of CDW order in SrAl₄ at 243K, together with a hysteretic structural transition at 87K that is thought to be a structural transition to a monoclinic system. The tetragonal structure of BaAl₄ has also recently been shown to have topologically non-trivial bands and has lattice parameters very close to SrAl₄. In order to study the interplay between these features we have done a chemical substitution study to track the reported transitions. We have performed electrical resistivity measurements, along with x-ray and neutron scattering on the Ba_1-xSr_xAl₄ family. We show a suppression of the CDW order with increased Ba substitution. Neutron scattering and x-ray measurements show the nature of the CDW.