Temperature-driven change in band structure reflecting spin-charge separation of Mott and Kondo insulators

Abstract

The electronic band structure can change with temperature in Mott and Kondo insulators, even without a phase transition. Here, to clarify the underlying mechanism, the spectral function at nonzero temperature is studied. By considering selection rules, the spin excited states of Mott and Kondo insulators, whose excitation energies are lower than the charge gap, are shown to emerge in the electronic spectral function at nonzero temperature, exhibiting momentum-shifted magnetic dispersion relations from the band edges, as in the case of the doping-driven Mott transition at zero temperature. Based on this characteristic, we interpret the numerical results for temperature-driven change in band structure in the one- and two-dimensional and ladder Hubbard models and one-dimensional periodic Anderson model at half filling obtained using cluster perturbation theory with the low-temperature Lanczos method. This characteristic also explains why the band structures can change with temperature even in the energy regime far higher than the temperature and why spectral weights emerge in the energy regime within the band gap, where excitation energies are lower than the lowest electronic excitation energy from the ground state. Furthermore, if the band width of the spin excitation is comparable to the band gap, the emergent electronic modes can cross the Fermi level and gain spectral weight as the temperature increases, which leads to an insulator-metal crossover. These features are primarily caused by the spin excited states that are transparent in electronic measurements at zero temperature, in contrast to the conventional view where thermal effects on electron-added and removed states and static spin correlations are considered to mainly affect the band structure. This innovative perspective provides a different understanding from the conventional view on electronic states at nonzero temperatures.

19 pages, 9 figures, 3 tables

References in corpus (13)

• Evolution of electronic structure of doped Mott insulators - reconstruction of poles and zeros of Green's function
• Quantum Oscillations of Electrical Resistivity in an Insulator
• Fermi surface in the absence of a Fermi liquid in the Kondo insulator SmB${}_6$
• Doped high-Tc cuprate superconductors elucidated in the light of zeros and poles of electronic Green's function
• Low Temperature Lanczos Method
• Mott Transition in the Two-Dimensional Hubbard Model
• Composite-Fermion Theory for Pseudogap, Fermi Arc, Hole Pocket, and Non-Fermi-Liquid of Underdoped Cuprate Superconductors
• Spectral properties near the Mott transition in the two-dimensional Hubbard model with next-nearest-neighbor hopping
• Characteristics of the Mott transition and electronic states of high-temperature cuprate superconductors from the perspective of the Hubbard model
• Relationship between single-particle excitation and spin excitation at the Mott Transition
• Emergence and spectral-weight transfer of electronic states in the Hubbard ladder
• Spectral function of the $U\to \infty$ one dimensional Hubbard model at finite temperature and the crossover to the spin incoherent regime
• Emergence of electronic modes by doping Kondo insulators in the Kondo lattice and periodic Anderson models

Cited by in corpus (1)

• Emergence and evolution of electronic modes with temperature in spin-gapped Mott and Kondo insulators