Dirac semimetal PdTe2 temperature-dependent quasiparticle dynamics and electron-phonon coupling

Dirac semimetal PdTe2 single-crystal temperature-dependent ultrafast carrier and phonon dynamics were studied using ultrafast optical pump-probe spectroscopy. Quantitative analysis revealed a fast relaxation process (tau(f)) occurring at a subpicosecond time scale originating from electron-phonon thermalization. This rapid relaxation was followed by a slower relaxation process (tau(s)) on a time scale of similar to 7-9.5 ps which originated from phonon-assisted electron-hole recombination. Two significant vibrational modes resolved at all measured temperatures. These modes corresponded to in-plane (E-g), and out-of-plane (A(1g)), Te atoms motion. Test results suggested that pure dephasing played an important role in the relaxation processes. Analysis of the electron-phonon coupling constant suggested that the A(1g) mode contributes greatly to the superconductivity, and high-frequency phonons are also involved forming of Cooper pairs. Our observations should improve the understanding of complex superconductivity of PdTe2.

Automated summary

The study investigated the ultrafast carrier and phonon dynamics of Dirac semi-metal PdTe2 single-crystal using ultrafast optical pump-probe spectroscopy. It revealed fast relaxation process from electron-phonon thermalization and slower relaxation process from phonon-assisted electron-hole recombination. The analysis suggested the A(1g) mode contributes greatly to superconductivity and high-frequency phonons are involved in forming Cooper pairs in PdTe2.