4 research outputs found
Spectral microscopic mechanisms and quantum phase transitions in a 1D correlated problem
In this paper we study the dominant microscopic processes that generate
nearly the whole one-electron removal and addition spectral weight of the
one-dimensional Hubbard model for all values of the on-site repulsion . We
find that for the doped Mott-Hubbard insulator there is a competition between
the microscopic processes that generate the one-electron upper-Hubbard band
spectral-weight distributions of the Mott-Hubbard insulating phase and
finite-doping-concentration metallic phase, respectively. The spectral-weight
distributions generated by the non-perturbative processes studied here are
shown elsewhere to agree quantitatively for the whole momentum and energy
bandwidth with the peak dispersions observed by angle-resolved photoelectron
spectroscopy in quasi-one-dimensional compounds.Comment: 18 pages, 2 figure
The TTF finite-energy spectral features in photoemission of TTF-TCNQ: The Hubbard-chain description
A dynamical theory which accounts for all microscopic one-electron processes
is used to study the spectral function of the 1D Hubbard model for the whole
-plane, beyond previous studies which focused on the weight
distribution in the vicinity of the singular branch lines only. While our
predictions agree with those of the latter studies concerning the
tetracyanoquinodimethane (TCNQ) related singular features in photoemission of
the organic compound tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ)
metallic phase, the generalized theory also leads to quantitative agreement
concerning the tetrathiafulvalene (TTF) related finite-energy spectral
features, which are found to correspond to a value of the on-site repulsion
larger than for TCNQ. Our study reveals the microscopic mechanisms behind the
unusual spectral features of TTF-TCNQ and provides a good overall description
of those features for the whole -plane.Comment: To appear in Journal of Physics: Condensed Matte
Scattering mechanisms and spectral properties of the one-dimensional Hubbard model
It is found that the finite-energy spectral properties of the one-dimensional
Hubbard model are controlled by the scattering of charged -spin-zero
-holon composite objects, spin-zero -spinon composite objects, and
charged -spin-less and spin-less objects, rather than by the scattering
of independent -spin 1/2 holons and spin 1/2 spinons. Here . The corresponding matrix is calculated and its relation to the
spectral properties is clarified.Comment: 8 pages, no figure
Spinon and η -spinon correlation functions of the Hubbard chain
We calculate real-space static correlation functions of spin and charge degrees of freedom of the
one-dimensional Hubbard model that are described by operators related to singly occupied sites with spin
up or spin down (spinons) and unoccupied or doubly occupied sites ( η -spinons). The spatial decay of their
correlation functions is determined using density matrix renormalization group results. The nature and
spatial extent of the correlations between two sites on the Hubbard chain is studied using the eigenstates
and eigenvalues of the two-site reduced density matrix. The results show that the spinon-spinon correlation
functions decay algebraically and the η -spinon correlation functions decay exponentially, both in the half-
filling and metallic phases. The results provide evidence that these degrees of freedom are organized in
boundstates in the interacting system.Portuguese FCT both in the frame-
work of the Strategic Project PEST-C/FIS/UI607/2011 and
under SFRH/BSAB/1177 /201