On the possibility of an excitonic insulator at the semiconductor-semimetal transition

Abstract

We calculate the critical temperature below which an excitonic insulator exists at the pressure-induced semiconductor-semimetal transition. Our approach is based on an effective-mass model for valence and conduction band electrons interacting via a statically screened Coulomb potential. Assuming pressure to control the energy gap, we derive, in the spirit of a BEC-BCS crossover scenario, a set of equations which determines, as a function of the energy gap (pressure), the chemical potentials for the two bands, the screening wave number, and the critical temperature. We (i) show that in leading order the chemical potentials are not affected by the exciton states, (ii) verify that on the strong coupling (semiconductor) side the critical temperatures obtained from the linearized gap equation coincide with the transition temperatures for BEC of non-interacting bosons, (iii) demonstrate that mass asymmetry strongly suppresses BCS-type pairing, and (iv) discuss in the context of our theory recent experimental claims for exciton condensation in $\mathrm{TmS}{\mathrm{e}}_{0.45}\mathrm{T}{\mathrm{e}}_{0.55}$.

16 pages, 8 figures, revised version, including a short discussion of electron-hole liquids vs. excitonic phases

References in corpus (3)

• BCS-BEC crossover at finite temperature in the broken-symmetry phase
• Models of coherent exciton condensation
• Coherent transport in homojunction between excitonic insulator and semimetal

Cited by in corpus (43)

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• Spontaneous exciton condensation in 1T-TiSe2: a BCS-like approach
• Flat-Bands-Enabled Triplet Excitonic Insulator in a Di-atomic Kagome Lattice
• Critical Temperature Curve in the BEC-BCS Crossover
• Bound state formation and nature of the excitonic insulator phase in the extended Falicov-Kimball model
• Non-Coulomb strong electron-hole binding in $T{a}_{2}NiS{e}_5$ revealed by time- and angle-resolved photoemission spectroscopy
• Impact of Electron-Hole Correlations on the 1T-TiSe2 Electronic Structure
• Fate of the excitonic insulator in the presence of phonons
• Charge-density wave induced by combined electron-electron and electron-phonon interactions in 1$T$-TiSe${}_2$: A variational Monte Carlo study
• Phononic soft mode and strong electronic background behavior across the structural phase transition in the excitonic insulator Ta${}_2$NiSe${}_5$ (with Erratum)
• Bulk Photovoltaic Effect Driven by Collective Excitations in a Correlated Insulator
• Correlation effects in partially ionized mass asymmetric electron-hole plasmas
• Doping-controlled transition from excitonic insulator to semimetal in Ta${}_2$NiSe${}_5$
• Hybridization-gap Formation and Superconductivity in the Pressure-induced Semimetallic Phase of the Excitonic Insulator Ta${}_2$NiSe${}_5$
• A New Era of Excitonic Insulators
• Electric and magnetic multipoles and bond orders in excitonic insulators
• Orbital diamagnetic susceptibility in excitonic condensation phase
• Anomalous excitonic phase diagram in band-gap-tuned Ta2Ni(Se,S)5
• Quantum anomalous Hall effect and electric-field-induced topological phase transition in AB-stacked MoTe${}_2$/WSe${}_2$ moiré heterobilayers
• Excitonic insulator emerging from semiconducting normal state in $1T$-TiSe${}_2$
• Ultrafast charge carrier and exciton dynamics in an excitonic insulator probed by time-resolved photoemission spectroscopy
• Evolution of the electronic structure in Ta${}_2$NiSe${}_5$ across the structural transition revealed by resonant inelastic x-ray scattering
• Photoinduced metallization of excitonic insulators
• Effects of Disorder on the Transport of Collective Modes in an Excitonic Condensate
• Excitonic Insulator State of the Extended Falicov-Kimball Model in the Cluster Dynamical Impurity Approximation
• Finite-temperature photoemission in the extended Falicov-Kimball model: a case study for Ta${}_2$NiSe${}_5$
• Excitonic condensation reflecting electronic states in two-band Penrose-Hubbard model
• Excitonic Insulator to Superconductor Phase Transition in Ultra-Compressed Helium
• Competing phases in a model of Pr-based cobaltites
• Third-harmonic generation in excitonic insulators
• Assignment of excitonic insulators in \textit{ab initio} theories: the case of NiBr${}_2$
• Excitonic insulators and Gross-Neveu models
• Generalizing Planck's Law: Nonequilibrium Emission of Excited Media
• Theory of Thermal Conductivity on Excitonic Insulator
• Exciton formation in strongly correlated electron-hole systems near the semimetal-semiconductor transition
• Detecting photoelectrons from spontaneously formed excitons
• Elastic Soft Mode and Electric Quadrupole Response in Excitonic Insulator Candidate (Ta${}_{0.952}$V${}_{0.048}$)${}_2$NiSe${}_5$: Contribution of Electron-Phonon Interaction
• Anomalous 4$f$ fine structure in TmSe${}_{1-x}$Te${}_x$ across the metal-insulator transition
• Unveiling Excitonic Insulator Signatures in Ta${}_2$NiSe${}_5$
• Localized excitons in 1D half-filled paramagnetic Hubbard model
• BCS-BEC crossover of polaritonic condensates in mass-imbalanced semimetal/semiconductor microcavities
• Long-lived relaxation channel and exciton-phonon coupling in Ta2NiSe5 via non-degenerate pump-probe spectroscopy