Berlin 2024 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 39: Correlated Electrons: Charge Order
TT 39.4: Vortrag
Mittwoch, 20. März 2024, 10:15–10:30, H 3025
Giant circular dichroism induced by electronic chirality in TiSe2 — Qian Xiao1, •Oleg Janson2, Sonia Francoual3, Qingzheng Qiu1, Qizhi Li1, Shilong Zhang1, Wu Xie3,4, Pablo Bereciartua3, Jeroen van den Brink2,5,6, Jasper van Wezel6, and Yingying Peng1,7 — 1Peking University, Beijing, China — 2Institute for Theoretical Solid State Physics, Leibniz IFW Dresden, Germany — 3DESY, Hamburg, Germany — 4Zhejiang University, Hangzhou, China — 5Würzburg-Dresden Cluster of Excellence ct.qmat, Germany — 6Institute for Theoretical Physics, University of Amsterdam, The Netherlands — 7Collaborative Innovation Center of Quantum Matter, Beijing, China
The quasi-2D van-der-Waals material 1T-TiSe2 is known for its well-studied transition into a commensurate 2×2×2 charge density wave (CDW) state. Several experimental and theoretical studies suggested that the charge order may be chiral, yet no bulk measurement so far provided direct evidence for intrinsic broken inversion symmetry and chirality. In a resonant elastic x-ray scattering (REXS) experiment, we observe giant circular dichroism up to ∼40% at a Bragg peak forbidden in the centrosymmetric CDW structure. By performing first-principles calculations for the earlier proposed chiral structural model, we find excellent quantitative agreement with the experimental azimuthal angle dependence for different polarizations. In this way, we accurately estimate the magnitude of the inversion-breaking distortion and confirm that bulk 1T-TiSe2 has chiral electronic order.
Keywords: charge density wave (CDW); inversion symmtery breaking; orbital ordering; resonant elastic x-ray scattering (REXS); transition-metal dichalcogenides (TMD)