Origin of charge density waves in the tetragonal Eu(Ga,Al)4 series studied by IXS

The tetragonal compounds Eu(Ga,Al)4 exhibit unusual interplay between the charge-density wave stability and applied hydrostatic pressure. Depending on the Ga and Al stoichiometry, the CDW transition can be either suppressed or induced. Recently, we managed to observe a soft-phonon mode, which precedes the CDW order in EuAl4. In the proposed experiment we intend to observe similar softening in EuGa4 under applied pressure to understand its physics.