Photoinduced electron-electron pairing in the extended Falicov-Kimball model

Abstract

By employing the time-dependent exact diagonalization method, we investigate the photoexcited states of the excitonic insulator in the extended Falicov-Kimball model (EFKM). We here show that the pulse irradiation can induce the interband electron-electron pair correlation in the photoexcited states, while the excitonic electron-hole pair correlation in the initial ground state is strongly suppressed. We also show that the photoexcited states contains the eigenstates of the EFKM with a finite number of interband electron-electron pairs, which are responsible for the enhancement of the electron-electron pair correlation. The mechanism found here is due to the presence of the internal SU(2) pairing structure in the EFKM and thus it is essentially the same as that for the photoinduced $\eta$-pairing in the repulsive Hubbard model reported recently [T. Kaneko et al., Phys. Rev. Lett. $122$, 077002 (2019)]. This also explains why the nonlinear optical response is effective to induce the electron-electron pairs in the photoexcited states of the EFKM. Furthermore, we show that, unlike the $\eta$-pairing in the Hubbard model, the internal SU(2) structure is preserved even for a nonbipartite lattice when the EFKM has the direct-type band structure, in which the pulse irradiation can induce the electron-electron pair correlation with momentum $\mathbf{q}$ = $\text{0}$ in the photoexcited states. We also discuss briefly the effect of a perturbation that breaks the internal SU(2) structure.

15 pages, 13 figures

References in corpus (14)

• Evidence for an excitonic insulator phase in 1T-TiSe${}_2$
• Theoretical description of time-resolved photoemission spectroscopy: application to pump-probe experiments
• Excitonic Bose-Einstein condensation in Ta2NiSe5 above room temperature
• Spontaneous exciton condensation in 1T-TiSe2: a BCS-like approach
• Theory of Laser-Controlled Competing Superconducting and Charge Orders
• Photo-induced enhancement of excitonic order
• Revealing the role of electrons and phonons in the ultrafast recovery of charge density wave correlations in 1$T$-TiSe${}_2$
• Bound state formation and nature of the excitonic insulator phase in the extended Falicov-Kimball model
• Charge-density wave induced by combined electron-electron and electron-phonon interactions in 1$T$-TiSe${}_2$: A variational Monte Carlo study
• Theory for Time-Resolved Resonant Inelastic X-ray Scattering
• Producing Coherent Excitations in Pumped Mott Antiferromagnetic Insulators
• Enhanced charge order in a photoexcited one-dimensional strongly correlated system
• Electric and magnetic multipoles and bond orders in excitonic insulators
• Excitonic Insulator State of the Extended Falicov-Kimball Model in the Cluster Dynamical Impurity Approximation

Cited by in corpus (3)

• Photoinduced $\eta$-pairing at finite temperatures
• Photo-induced Dirac cone flattening in BaNiS${}_2$
• Steady off-diagonal long-range order state in a half-filled dimerized Hubbard chain induced by a resonant pulsed field