Article Dans Une Revue Physical Review B Année : 2025

Conduction Band Structure and Ultrafast Dynamics of Ferroelectric α-GeTe(111)

Résumé

α-GeTe( 111) is a non-centrosymmetric ferroelectric (FE) material for which a significative lattice distortion combined with a strong spin-orbit interaction gives rise to giant Rashba split states in the bulk and at the surface, which have been intensively probed in the occupied valence states using static angle-resolved photoemission spectroscopy (ARPES). Nevertheless, its unoccupied conduction band structure remains unexplored, in particular the experimental determination of its electronic band gap across momentum space. Using time-resolved ARPES based on high-repetition rate and extreme ultraviolet femtosecond (fs) laser, we unveil the band structure of α-GeTe(111) in the full Brillouin zone, both in the valence and conduction states, as well as the exploration of its out-ofequilibrium dynamics. Our work confirms the semiconducting nature of α-GeTe(111) with a 0.85 eV indirect band gap, which provides an upper limit for comparison to density functional theory calculations. We finally reveal the dominant scattering mechanisms of photoexcited carriers during the out-of-equilibrium dynamics under fs light pulses.

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Dates et versions

hal-05060645 , version 1 (08-05-2025)
hal-05060645 , version 2 (03-06-2025)

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Geoffroy Kremer, Laurent Nicolaï, Frédéric Chassot, Julian Maklar, Christopher W Nicholson, et al.. Conduction Band Structure and Ultrafast Dynamics of Ferroelectric α-GeTe(111). Physical Review B, 2025, 111 (235109), ⟨10.1103/PhysRevB.111.235109⟩. ⟨hal-05060645v2⟩
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