Cluster charge-density-wave glass in hydrogen-intercalated TiSe$_{2}$

TL;DR

This study investigates hydrogen-intercalated TiSe₂ using NMR, revealing mesoscopic charge-density wave domains with glassy dynamics and localized phason-like motions influenced by structural defects.

Contribution

It introduces NMR as a local probe to study charge-density wave dynamics and uncovers glassy behavior and defect-induced localization in hydrogen-intercalated TiSe₂.

Findings

Mesoscopic charge-density wave domains exhibit cluster-glass-like dynamics.

A distinct low-temperature process linked to charge-density wave phason motion.

Structural defects hinder collective charge-density wave excitations.

Abstract

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 1$T$-TiSe$_{2}$, 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 1$T$-TiSe$_{2}$ 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 the $^{1}$H 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 phason-like motion of the charge-density wave being hindered by structural defects and chemical impurities and resulting in a localized oscillating motion.