Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 29: 2D Materials: Electronic Structure and Exitations I (joint session O/HL/TT)

O 29.5: Vortrag

Dienstag, 18. März 2025, 11:30–11:45, H8

Enhanced electron-phonon coupling in few-layer MoTe₂ from micro-ARPES — •Thomas P. van Waas¹, Julia Issing², Marco Gibertini³, Christophe Berthod², Anna Tamai², Felix Baumberger^2,4, and Samuel Poncé^{1, 5} — ¹European Theoretical Spectroscopy Facility, Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Belgium — ²Department of Quantum Matter Physics, University of Geneva, Switzerland — ³Dipartimento di Scienze Fisiche, Informatiche e Matematiche, University of Modena and Reggio Emilia, Italy — ⁴Swiss Light Source, Paul Scherrer Institut, Switzerland — ⁵WEL Research Institute, Belgium

Bulk orthorhombic T_d-MoTe₂ is a type-II Weyl semimetal with a superconducting critical temperature of T_c=0.1 K. Transport measurements show a monotonic increase in T_c as the thickness of multilayer MoTe₂ is reduced, reaching T_c=7.6 K in the monolayer. We investigate photoemission kinks in the electron pocket of exfoliated mono- bi-, and trilayer MoTe₂ from micro-focused angle-resolved photoemission spectroscopy. We use a custom code to quantify the electron self-energy Σ_n(E) for a parabolic non-interacting dispersion, and obtain from Σ_n(E) the Eliashberg spectral function α²F_n(ω) using the maximum entropy method. We find two dominant phonon modes in α²F_n(ω) for the mono- and trilayer, with a large enhancement of the lower-frequency phonon mode in the former. We also provide tentative results for the bilayer, where quantification is more challenging due to a small splitting of the electronic bands.

Keywords: ARPES; Phonons; Self-energy; Eliashberg; Superconductivity