APS Global Physics Summit Logo March 16–21, 2025, Anaheim, CA and virtual
Contributed Session
March

Charge Density Waves and Electron Phonon Coupling

11:30 am – 2:30 pm, Wednesday March 19 Session MAR-M26 Anaheim Convention Center, 251B (Level 2)
Chair:
Jack Simonson, State Univ of NY - Farmingdale
Topics:
Sponsored by
DCMP

Substitution-dependent orbital character of the electronic structure in Ta2NiSe5 and derivatives

1:54 pm – 2:06 pm
Presenter: Stefan Schuppler (Karlsruhe Institute of Technology)
Authors: Nour Maraytta (Karlsruhe Institute of Technology), Peter Nagel (Karlsruhe Institute of Technology), Fatemeh Ghorbani (Karlsruhe Institute of Technology), Amir Ghiami (Karlsruhe Institute of Technology), Santanu Pakhira (Karlsruhe Institute of Technology), Mai Ye (Karlsruhe Institute of Technology), Björn Wehinger (ESRF), Federico Abbruciati (ESRF), Gaston Garbarino (ESRF), Matthieu Le Tacon (Karlsruhe Institute of Technology), Amir-Abbas Haghighirad (Karlsruhe Institute of Technology), Michael Merz (Karlsruhe Institute of Technology)

Ni L-edge x-ray absorption (XAS) was used to study the electronic structure of the Ta2NiSe5 family, including substitutions on the Ni site (by Co) and on the Se site (by S). This is a “candidate” for the yet elusive realization of an excitonic insulator (EI). The polarization dependence of XAS indicates the orbital character of the Ni 3d states involved in the temperature-driven structural transitions (one for each composition) that were determined and studied by high-resolution x-ray diffraction. In the complex interplay between electronic structure, spatial structure, and orbital character we observe a systematic evolution with substitution, moving between phase-space regions with somewhat insulating, small-gap, or slightly semimetallic character. Taken together, the results may augment our understanding of the electronic and structural properties conducive for EI behavior.

We acknowledge the KIT Light Source, the KNMFi, and the European Synchrotron Radiation Facility (ESRF) for provision of synchrotron radiation facilities.

PRESENTATIONS (15)