A Phonon Study of the Charge Density Wave/Superconductor 2H-TaS2

The proposed experiment is an inelastic x-ray scattering study to map the temperature dependence of the phonon dispersion in the transition metal dichalcogenide (TMD) 2H-TaS2. 2H-TaS2 has been shown to form a charge density wave (CDW) below ~76 K. Here, we want to observe the collapse of the phonon as the CDW is formed, at the CDW q vector (0.341, 0, 0)a*. 2H-TaS2 has also been shown to be superconducting below ~1 K, with a strong crystallographic anisotropy. As seen in other TMD materials, the superconducting state could be heavily affected by the CDW state, specifically, the anisotropy. Therefore, studying the nature of the CDW state can give us information about both the CDW state as well as the superconducting state.