Persistence of charge ordering instability to Coulomb engineering in the excitonic insulator candidate TiSe
arXiv:2506.01470 · doi:10.1103/9trc-9865
Abstract
TiSe has long been considered one of the best candidate materials to host the elusive excitonic insulator (EI) phase. However, a finite coupling to the lattice can generically be expected, while a lack of "smoking-gun" signatures for the importance of the electron-hole interaction in driving the phase transition has rendered it challenging to distinguish the EI from the conventional charge-density-wave (CDW) phase. Here, we demonstrate a new approach, exploiting the susceptibility of excitons to dielectric screening. We combine mechanical exfoliation with molecular-beam epitaxy to fabricate ultra-clean van der Waals heterostructures of monolayer (ML-)TiSe/graphite and ML-TiSe/hBN. We observe how the modified substrate screening environment drives a renormalisation of the quasi-particle band gap of the TiSe layer, signifying its susceptibility to Coloumb engineering. The temperature-dependent evolution of its electronic structure, however, remains unaffected, indicating that excitons are not required to drive the CDW transition in TiSe.
arXiv comment15 pages including supplemental information, 5+4 figures
References in corpus (39)
- Observation of tightly bound trions in monolayer MoS2
- Exciton Binding Energy and Nonhydrogenic Rydberg Series in Monolayer WS2
- Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
- Probing Excitonic Dark States in Single-layer Tungsten Disulfide
- Evidence for an excitonic insulator phase in 1T-TiSe
- Controlling many-body states by the electric-field effect in a two-dimensional material
- Signatures of exciton condensation in a transition metal dichalcogenide
- TRIQS: A Toolbox for Research on Interacting Quantum Systems
- Non-thermal separation of electronic and structural orders in a persisting charge density wave
- Excitons versus electron-hole plasma in monolayer transition metal dichalcogenide semiconductors
- Nanoscale capillary freezing of ionic liquids confined between metallic interfaces and the role of electronic screening
- Evidence for equilibrium excitons and exciton condensation in monolayer WTe2
- Rigid band shifts in two-dimensional semiconductors through environmental screening
- Renormalization of quasiparticle band gap in doped two-dimensional materials from many-body calculations
- Temperature dependent photoemission on 1T-TiSe2: Interpretation within the exciton condensate phase model
- Orbital- and -selective hybridisation of Se 4p and Ti 3d states in the charge density wave phase of TiSe
- Wannier Function Approach to Realistic Coulomb Interactions in Layered Materials and Heterostructures
- Development of Density-Functional Theory for Plasmon-Assisted Superconducting State: Application to Lithium Under High Pressures
- Revealing the role of electrons and phonons in the ultrafast recovery of charge density wave correlations in 1-TiSe
- Dielectric permittivity, conductivity and breakdown field of hexagonal boron nitride
- Dependence of the hBN Layer Thickness on the Band Structure and Exciton Properties of Encapsulated WSe2 Monolayers
- Evidences for the exciton gas phase and its condensation in monolayer 1T-ZrTe2
- Morphology Control of Epitaxial Monolayer Transition Metal Dichalcogenides
- Evidence of high-temperature exciton condensation in a two-dimensional semimetal
- Excitation-induced transition to indirect band gaps in atomically thin transition metal dichalcogenide semiconductors
- Random Phase Approximation for gapped systems: role of vertex corrections and applicability of the constrained random phase approximation
- Role of electron-phonon coupling in excitonic insulator candidate Ta2NiSe5
- Phonon Self-Energy Corrections: To Screen, or Not to Screen
- Coulomb-Engineered Heterojunctions and Dynamical Screening in Transition Metal Dichalcogenide Monolayers
- Electronic Structure of Exfoliated and Epitaxial Hexagonal Boron Nitride
- Dramatic Plasmon Response to the Charge-Density-Wave Gap Development in
- Enhancing charge-density-wave order in 1T-TiSe2 nanosheet by encapsulation with hexagonal Boron Nitride
- Observation of possible excitonic charge density waves and metal-insulator transitions in atomically thin semimetals
- Evidence for an Excitonic Insulator State in TaPdTe
- Coulomb Engineering of two-dimensional Mott materials
- Lattice fluctuations, not excitonic correlations, mediated electronic localization in TiSe
- Molecular Beam Epitaxy growth of MoTe on Hexagonal Boron Nitride
- Ab initio electron-lattice downfolding: potential energy landscapes, anharmonicity, and molecular dynamics in charge density wave materials
- Quasiparticle gap renormalization driven by internal and external screening in a WS device