2024/11/27 by Vikas Arora, Arora, Vikas, Victor S Muthu +9
Engineering · Materials Science · Physics and Astronomy · #2D Materials and Applications #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Perovskite Materials and Applications #Semiconductor Quantum Structures and Devices
paper · pdf · doi:10.48550/arxiv.2411.18031
openalex publication_date 2024/11/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
An excitonic insulator (EI) phase is a consequence of collective many-body effects where an optical band gap is formed by the condensation of electron-hole pairs or excitons. We report pressure-dependent optical pump optical probe spectroscopy of EI Ta2NiSe5 in an on-site in situ geometry. The fast relaxation process depicts the transition across PC1 ∼1 GPa from EI phase to a semiconductor and PC2 ∼3 GPa from a semiconductor to a semimetallic phase. The instability of the EI phase beyond PC1 is captured by the Rothwarf-Taylor model by incorporating the decrease of the bandgap under pressure. The pressure coefficient of the bandgap decreases, 65 meV/GPa closely agrees with the first principle calculations.