Charge density waves and soft phonon evolution in the superconductor BaNi$_2$(As$_{1-x}$P$_x$)$_2$ [Dataset]

The superconductor BaNi$_2$As$_2$ exhibits a soft-phonon-driven, incommensurate charge density wave (I-CDW) which emerges in the vicinity of an orthorhombic structural phase transition. Upon further cooling, BaNi$_2$As$_2$ undergoes a first-order structural transition to a triclinic phase in which a commensurate CDW (C-CDW) emerges. The relationship and interplay between the I-CDW, C-CDW and structural phase transitions has remained elusive. To investigate this issue, we present a complementary study of thermal diffuse X-Ray scattering and inelastic X-Ray scattering of both the I-CDW and C-CDW for phosphorus substituted BaNi$_2$(As$_{1-x}$P$_x$)$_2$ up to \(x\approx0.12\) and down to 2.2 K.