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Mott transition
About: Mott transition is a research topic. Over the lifetime, 2444 publications have been published within this topic receiving 78401 citations.
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01 Feb 2009
TL;DR: In this article, the authors investigated the exciton Mott transition and pair condensation in the spinless electron-hole Hubbard model by means of the dynamical mean field theory combined with the noncrossing approximation.
Abstract: We investigate the exciton Mott transition and pair condensation in the spinless electron-hole Hubbard model by means of the dynamical mean field theory combined with the noncrossing approximation. By investigating the single-particle density of states, we find the crossover between the metallic electron-hole plasma and the exciton-like insulator. We also investigate the electron-hole pair condensation transition and the optical response, by calculation of the two-particle Green's function for the pair correlation with vertex corrections. It is shown that the excitonic peak in the optical response function gets strongly enhanced around the electron-hole pair condensation transition.
TL;DR: In this paper, the authors consider the low-temperature differential tunneling conductance for interfaces between a planar insulating material in the Mott-class and a metal.
Abstract: We consider the low-temperature differential tunneling conductance $G$ for interfaces between a planar insulating material in the Mott-class and a metal. For values of the the applied potential difference $V$ that are not very small, there is a experimentally observed universal regime in which $G \sim V^m$, where $m$ is a universal exponent. We consider the theoretical prediction of the values of $m$ by using the method of Effective Field Theory ($EFT$), which is appropriate for discussing universal phenomena. We describe the Mott material by the $EFT$ pertaining the long-distance behavior of a spinless Hubbard-like model with nearest neighbors interactions previously considered. At the Mott transition, the $EFT$ is known to be given by a double Abelian Chern-Simons theory. The simplest realization of this theory at the tunneling interface yields a Conformal Field Theory with central charges $(c,\bar c) =(1,1)$ and Jain filling fraction $
u = 2/3$ describing a pair of independent counter-propagating chiral bosons (one charged and one neutral). Tunneling from the material into the metal is, therefore, described by this $EFT$ at the Mott critical point. The resulting tunneling conductance behaves as $G \sim V^{(1/
u -1)}$, yielding the prediction $m=1/2$, which compares well (within a $10 \%$ deviation) with the results for this exponent in two experimental studies considered here.
01 Feb 2009
TL;DR: In this paper, an extension of the dynamical mean field theory (DMFT) for the continuous-space model of the electron-hole (e-h) system is presented.
Abstract: We study the exciton Mott transition in the three-dimensional electron-hole (e-h) system by means of an extension of the dynamical mean field theory (DMFT). In order to apply DMFT to the e-h system with the contact e-h attraction v, we construct DMFT for the continuous-space model by introducing the short wavelength cut-off. Using the generalized formulation of DMFT, we calculate the temperature dependence of the single-particle density of states and the exciton density. We demonstrate that the system crossovers from metal to insulator as v increases, and finally determine the phase diagram.
TL;DR: In this paper, a geometrically frustrated Hubbard model on the checkerboard lattice with nearest neighbor (t) and diagonal (t ) hoppings was studied, and it was found that the increase of Coulomb interaction induces a first-order Mott transition to the plaquette singlet insulating (PSI) phase for t ≥ 1.0, which naturally leads to the P-VBC phase in the Heisenberg limit.
Abstract: We study a geometrically frustrated Hubbard model on the checkerboard lattice with nearest neighbor (t) and diagonal ( t ′ ) hoppings. By using the path-integral renormalization group method, we calculate the double occupancy and the plaquette singlet correlation function to discuss the instability of the plaquette valence-bond crystal (P-VBC) phase at half filling. It is found that the increase of Coulomb interaction induces a first-order Mott transition to the plaquette singlet insulating (PSI) phase for t ′ / t = 1.0 , which naturally leads to the P-VBC phase in the Heisenberg limit. For t ′ / t = 0.8 , the double quantum phase transitions occur, and the PSI phase is stabilized between paramagnetic metallic and antiferromagnetic insulating phase.
TL;DR: In this article, the authors present a theory of exciton formation in the upper Hubbard band and demonstrate that the effective Hamiltonian representing propagation and interaction of these particles has a dual form which reflects the particle-hole symmetry.
Abstract: Motivated by recent Raman and resonant inelastic X-ray scattering experiments performed for Mott insulators, which suggest existence of excitons in these systems, we present a theory of exciton formation in the upper Hubbard band These objects consist of a hole and a double occupancy We demonstrate that the effective Hamiltonian representing propagation and interaction of these particles has a dual form which reflects the particle-hole symmetry The analytical analysis of this Hamiltonian is based on the spin polaron approach The results confirm existence of excitons and show resemblance with experimental data despite the crudeness of the approach The driving mechanism of exciton formation is the kinetic energy saving achieved by formation of a spin bipolaron consisting of a hole and a double occupancy connected by a line formed by spin defects in the antiferromagnetic background which moves freely by expanding at one end of the line and shrinking at the other Our results also demonstrate that even if the Coulomb attraction between the hole and the double occupancy is screened, bound states will form and that the underlying mechanism of the exciton formation is similar to that of pairing in weakly doped antiferromagnets