2025/12/16 by Frédéric Chassot, Chassot, Frédéric, Aki Pulkkinen +9
Materials Science · Physics and Astronomy · #2D Materials and Applications #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Phase-change materials and chalcogenides #Strongly Correlated Electrons (cond-mat.str-el) #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.2512.14597
openalex publication_date 2025/12/16 · openalex created_date 2025/12/18 · openalex updated_date 2026/07/28
The ferroelectric semiconductor α-GeTe(111) has attracted significant attention in the last decade due to its unique properties, with extensive studies focusing on its occupied electronic bandstructure. In contrast, its unoccupied states - particularly those near the conduction band minimum - remain largely unexplored. In an effort to characterize those states, we surprisingly observe three image potential states (IPS) in α-GeTe(111) extending up to 0.8 eV above the vacuum level. Using time and angle-resolved photoemission spectroscopy, we resolve the full parabolic dispersions of the first three IPS and determine their binding energies. Our analysis, combined with Bloch spectral function calculations, reveals that the unexpected persistence of IPS above the vacuum level originates from strong dipole transitions and the presence of large electron reservoirs in GeTe.