Evolution of structural, magnetic and charge order in AAl4 series (A=Ba,Sr,Eu)

BaAl4 and its derived crystal structures host a variety of complex phenomena, including high-temperature superconductivity, charge and spin-density waves, and various topological phases. The SrAl4 and EuAl4 compounds have been reported to show CDW order at 243K and 140K respectively, however the BaAl4 compound contains no such order. Here, we report chemical substitution studies of the Ba1-xEuxAl4 and Ba1-xSrxAl4 compounds containing electrical resistivity, magnetic susceptibility, and x-ray measurements. CDW order spontaneously appears at critical Eu and Sr substitution near x = 0.7, after which it slowly increases to its maximum at x = 1. We present a study of structural and charge order in these series.