Cluster charge-density-wave glass in hydrogen-intercalated TiSe₂

The topotactic intercalation of transition-metal dichalcogenides with atomic or molecular ions acts as an efficient knob to tune the electronic ground state of the host compound. A representative material in this sense is 1T -TiSe2, where the electric-field-controlled intercalations of lithium or hydrogen trigger superconductivity coexisting with the charge-density-wave phase. Here, we use the nuclear magnetic moments of the intercalants in hydrogen-intercalated 1T -TiSe2 as local probes for nuclear magnetic resonance experiments. We argue that fluctuating mesoscopic-sized domains nucleate already at temperatures higher than the bulk critical temperature to the charge-density-wave phase and display cluster-glass-like dynamics in the MHz range tracked by 1H nuclear moments. Additionally, we observe a well-defined independent dynamical process at lower temperatures that we associate with the intrinsic properties of the charge-density-wave state. In particular, we ascribe the low-temperature phenomenology to the collective phasonlike motion of the charge-density wave being hindered by structural defects and chemical impurities and resulting in a localized oscillating motion.