Work

Collective modes and Raman response in Ta 2 NiSe 5

Year: 2025

Type: article

Abstract: We explore the collective response in an excitonic insulator phase in Ta 2 NiSe 5 using a semirealistic model including relevant lattice and electronic instabilities. We calculate order-parameter susceptibility and Raman response within a time-dependent Hartree-Fock approach. Contrary to the standard expectations, the amplitude mode frequency does not coincide with the single-particle gap but has a higher frequency. We find a phase mode that is massive because the excitonic condensation breaks a discrete symmetry only and that becomes heavier as the electron-lattice coupling is increased. These features are expected to apply to generic realistic excitonic insulators. We discuss scenarios under which the phase mode does not appear as a sharp in-gap resonance.

Source: Physical review. B./Physical review. B

DOI: 10.1103/physrevb.111.l121106

Authors: Banhi Chatterjee, Jernej Mravlje, Denis Golež

Institutions: Jožef Stefan Institute, Jožef Stefan International Postgraduate School, University of Ljubljana

Language: English

Topic: Physics of Superconductivity and Magnetism

Subfield: Condensed Matter Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Funder: Javna Agencija za Raziskovalno Dejavnost RS

Awards: G6741928566, Three advances towards realistic description of strongly correlated electron transport, Multi-scale modeling of non-equilibrium quantum materials, Solid state theory and statistical physics