Abstract:
Low-dimensional materials are promising for ultrafast electronics due to their unique charge-density-wave (CDW) states. In one-dimensional (1D) systems, Fermi surface nesting induces Kohn anomalies and collective amplitude modes. However, the mechanisms governing three-dimensional (3D) CDW phase transitions and collective dynamics remain a subject of debate. Among telluride materials, CuTe is notable for its structural simplicity. Using orientation-resolved pump-probe spectroscopy, we investigated the temperature-dependent evolution of ultrafast collective-amplitude-mode dynamics in (001) CuTe single crystals [1]. At 335 K, a 1D CDW with 1c periodicity forms along the a-axis. As temperature decreases, c-axis contraction induces quantum fluctuations that drive a dimensional transition from 1D to 3D CDW, accompanied by the emergence of ab-plane order. Below 220 K, the 3D CDW stabilizes with 2c periodicity and an anti-phase configuration along the c-axis, reaching a fully developed state through interlayer phase locking of the in-plane CDW. Additionally, Tb2Te5 single crystals were successfully grown via tellurium evaporation in boomerang-shaped quartz-glass ampoules [2]. The magnetic measurements reveal two antiferromagnetic orders at TN1 = 9.0 K and TN2 = 6.8 K. Transient reflectivity change spectra exhibit a rapid rise and ultrafast demagnetization driven by photoexcited carriers. The subsequent relaxation involves a fast (~ps) decay via electron-phonon coupling and a slower (~100 ps) process associated with magnetic order recovery, highlighting the intricate coupling between the magnetic and electronic subsystems in Tb2Te5.
Keywords – Collective amplitude mode, Charge density wave, Tellurides.
References
[1] N. N. Quyen et al., Nature Commun. 15, 2386 (2024).
[2] I. Shamova et al., Phys. Rev. B 112, 094434 (2025).