Nonlinear spectroscopy of collective modes in excitonic insulator

Abstract

The nonlinear optical response of an excitonic insulator coupled to lattice degrees of freedom is shown to depend in strong and characteristic ways on whether the insulating behavior originates primarily from electron-electron or electron-lattice interactions. Linear response optical signatures of the massive phase mode and the amplitude (Higgs) mode are identified. Upon nonlinear excitation resonant to the phase mode, a new in-gap mode at twice the phase mode frequency is induced, leading to a huge second harmonic response. Excitation of in-gap phonon modes leads to different and much smaller effects. A Landau-Ginzburg theory analysis explain these different behavior and reveals that a parametric resonance of the strongly excited phase mode is the origin of the photo-induced mode in the electron-dominant case. The difference in the nonlinear optical response serve as a measure of the dominant mechanism of the ordered phase.

References in corpus (12)

• Evidence of high-temperature exciton condensation in 2D atomic double layers
• Terahertz-Field-Induced Ferroelectricity in Quantum Paraelectric SrTiO${}_3$
• Metastable ferroelectricity in optically strained $SrTi{O}_3$
• Amplitude / Higgs Modes in Condensed Matter Physics
• Exciton Condensation and Perfect Coulomb Drag
• Excitonic Bose-Einstein condensation in Ta2NiSe5 above room temperature
• Spontaneous exciton condensation in 1T-TiSe2: a BCS-like approach
• Photo-induced enhancement of excitonic order
• Ultrafast evolution and transient phases of the prototype out-of-equilibrium Mott-Hubbard material V2O3
• Collective Modes in Excitonic Insulators: Effects of Electron-Phonon Coupling and Signatures in Optical Response
• Fate of the excitonic insulator in the presence of phonons
• Orthorhombic-to-monoclinic transition in Ta${}_2$NiSe${}_5$ due to a zone-center optical phonon instability

Cited by in corpus (14)

• Bulk Photovoltaic Effect Driven by Collective Excitations in a Correlated Insulator
• Second order Josephson effect in excitonic insulators
• A New Era of Excitonic Insulators
• Unveiling the underlying interactions in Ta2NiSe5 from photo-induced lifetime change
• Theory of competing excitonic orders in insulating WTe${}_2$ monolayers
• Leaky exciton condensates in transition metal dichalcogenide moiré bilayers
• Terahertz parametric amplification as a reporter of exciton condensate dynamics
• Graphene as a source of entangled plasmons
• Theory of time-crystalline behaviour mediated by phonon squeezing in Ta2NiSe5
• Third-harmonic generation in excitonic insulators
• Collective modes and Raman response in Ta${}_2$NiSe${}_5$
• Chirped amplitude mode in photo-excited superconductors
• Probing the collective excitations of excitonic insulators in an optical cavity
• Ab initio Approach to Collective Excitations in Excitonic Insulators