Title: Evolution of phases in AAl4 series (A = Ba, Sr, Eu, Ca, La)
Abstract: 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 charge-density wave (CDW) order at 243K and 140K respectively, however the other parent compounds in the series contain no such ordering. Recent investigation into the purity of the parent SrAl4 compound shows a strong sensitivity to the purity of Sr used in the growth procedure that leads to the presence of a hysteretic transition near T* ~ 85K. This transition has so far not been classified, though reports point to the possibility of a structural transition. In this talk, I will discuss the possible origins of the charge density wave ordering in the SrAl4 compound, as well as the behaviour of Tcdw, T*, and other properties of the compounds as a function of Ba, Ca, and La substitution onto the Sr site.