According to pressure-dependent x-ray powder\ndiffraction data the gap closure coincides with a structural phase transition.\nThe transition in TiOBr occurs at slightly lower pressure ($p$=14 GPa) compared\nto TiOCl ($p$=16 GPa) under hydrostatic conditions, which is discussed in terms\nof ...
The Mott-Hubbard (MH) band and the charge transfer gap in La 2 CuO 4 is investigated theoretically. The calculation of the band structure is made for the 5-orbital system of the CuO 4 plane which is composed by the usual CuO 2 plane plus O 2 at the two apical O sites. The ...
In particular, disorder can act to stabilize the Mott insulating gap in particle-hole symmetric models, whereas it destroys the gap if the symmetry is absent. This has interesting implications for the conductivity which will decrease with increasing disorder when the model is particle--hole ...
The incommensurate magnetic order leads to a pseudogap which opens at the Fermi energy and coexists with a large Mott-Hubbard gap. The quasiparticle states survive in the doped systems, but their dispersion is modified by the doping, and a rigid-band picture does not apply. Spectral weight in...
a pattern similar to the CDW order is visible deep in the Mott gap, exhibiting CDW without contribution of the Mott Hubbard band. Based on these findings in monolayer 1T-NbSe2, we provide novel insights into the relation between the correlated and collective electronic structures in monolayer 2D...
We study the metal-insulator transition and magnetic ordering in the Hubbard model using the particle-hole mapping. This representation facilitates the exact solution of the half-filled band in the limit of high spin. We find that the two-dimensional Hubbard model has a charge-excitation gap at...
We also study the changes in the density of statesacross the transition, which illustrate that the Fermi liquid breaks downbefore the gap opens.doi:10.1103/PhysRevLett.82.4890J. SchlipfM. JarrellP. G. J. van DongenNils BlümerDieter Vollhardt...
DMFTequationsbythenumericalrenormalizationgroupmethodatzerotemperature,andcalculatethespectraldensityasafunctionofdisorderstrength∆andinteractionUatdifferentfillings.Forfillingfactorsν=xor1+xthelowerorupperalloysubbandishalffilledandthesystembecomesaMottinsulatoratstronginteractions,withacorrelationgapatthe...
We develop a mean-field theory for this pairing which in a triangular lattice at T=0 leads to a first-order transition from a spiral, incommensurate metal to a commensurate insulator at U~=5.27t where a charge gap (~=0.085t) opens up. We also discuss the effect of fluctuations....
The resulting band structure shows one occupied and one empty surface band, separated by a direct band gap of 1.95 eV. Since the band gap in the spectrum of the Hubbard model is directly given by the on-site Coulomb-interaction parameter U of the dangling-bond orbital, our results allow ...