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HL: Fachverband Halbleiterphysik

HL 25: Poster 2D Materials: Electronic Structure and Exitations (joint session O/HL)

HL 25.6: Poster

Dienstag, 18. März 2025, 13:30–15:30, P3

Electronic and phononic characterization of 2H-NbS2 at the atomic scale — •Werner M.J. van Weerdenburg, Margarete Huisinga, and Katharina J. Franke — Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany

Transition metal dichalcogenides (TMDs) are a class of layered materials that can exhibit a variety of electronic properties, including low-temperature quantum phases such as superconductivity and charge density wave (CDW) formation. These phases may coexist, for instance in 2H-NbSe2, and electron-phonon interactions have been suggested as a common driving factor for the two phases [1]. In contrast, the similar compound 2H-NbS2 has a comparable superconducting critical temperature, but lacks a CDW phase [2], highlighting the importance of subtle differences in electron-phonon interactions.

Here, we apply scanning tunneling microscopy and spectroscopy (STM/STS) to investigate the electronic and phononic properties of 2H-NbS2 at the atomic scale. Based on quasiparticle interference mapping, we probe the spatial variation of the electronic density of states and identify the dispersion of the band structure around the Fermi level. Moreover, inelastic excitation spectroscopy reveals the phononic excitations of the material. By mapping the atomic-scale variation of phononic excitations around intrinsic defects of the material and adatoms, we study how electrons and phonons interact at the atomic scale.

[1] Rossnagel et al., PRB 64, 235119 (2001)

[2] Heil et al., PRL 119, 087003 (2017)

Keywords: Transition metal dichalcogenides; Superconductivity; Charge density wave; Scanning tunneling microscopy; 2D materials