Non-equilibrium electron dynamics of the bulk VSe2 charge-density-wave system

Wibke Bronsch,1 Manuel Tuniz,2 Denny Puntel,2 Alessandro Giammarino,2 Fulvio Parmigiani1,2 and Federico Cilento1

1Elettra – Sincrotrone Trieste S.C.p.A., Italy

2Dipartimento di Fisica, Università degli Studi di Trieste, Italy

By means of time- and angle-resolved photoemission spectroscopy (tr-ARPES), we investigate the effect of the charge density wave (CDW) phase transition on the equilibrium and out-ofequilibrium electronic properties of the transition metal dichalcogenide VSe2. The electronic band structure of VSe2 has recently been subject of investigation ranging from the bulk to the monolayer regime, in search for the manifestation of the opening of the band gap in its CDW phase [1,2]. However, at present, only a few studies on the effect of an ultrafast optical excitation are available [1,3]. In our contribution we present a study on the bulk material. By selecting the polarization of the probe pulses, tr-ARPES allows us to disentangle states with different orbital character, originating from the V and Se valence bands. When moving across the critical temperature of the CDW phase transition, our tr-ARPES data show indication for a change in the fast relaxation dynamics and for a different filling of novel photoinduced states near the Fermi level, lasting for several picoseconds after photoexcitation.

1. Biswas et al., Nano Letters 21, 1968-1975 (2021).
2. Umemoto et al., Nano Research 12, 165-169 (2019).
3. Majchrzak et al., arXiv:2011.06358v1 (2020).

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