Dresden 2026 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 21: Optical Analysis of Thin Films
DS 21.5: Vortrag
Freitag, 13. März 2026, 10:45–11:00, REC/C213
Spectroscopic Imaging Ellipsometry at Cryogenic Temperatures: Uncovering a Structural Phase Change in 2D Polar Ga — •Jakob Henz1, Arpit Jain2, Joshua A. Robinson2, Su Y. Quek3, and Ursula Wurstbauer3 — 1University of Münster — 2Center for 2DLM, PennState University — 3Centre for Advanced 2D Materials, National University of Singapore
2D polar metals are a class of atomically thin 2D materials, realized by confinement heteroepitaxial growth (CHet). Hereby, metal atoms are intercalated between a graphene and 6H-SiC interface1. This results in a large area, stable 2D metal film with a bonding gradient ranging from covalent over metallic to a vdW-interaction within only two to three atomic layers2.
Here, we use cryogenic spectroscopic imaging ellipsometry to investigate the temperature dependent light-matter interaction in bilayer 2D polar gallium down to 1 K.
Contrary to theoretical expectations1, we find a change in the local dielectric response of the material from a homogenous behavior at room temperature to a heterogenous regime at low temperatures, characterized by two absorption peaks localized to distinct surface areas on the sample3. This change is interpreted to indicate a structural phase transition in the material.
1 N. Briggs et al., Nat. Mater. 19.6, 637-643 (2020).
2 M. A. Steves et al., Nano Letters 20.11, 8312-8318 (2020).
3 J. Henz et al., in preparation (2025).
Keywords: Ellipsometry; SIE; Imaging; 2D Materials