11 research outputs found
Superconducting properties of the hole-doped three-band \emph{d-p} model studied with minimal-size real-space \emph{d}-wave pairing operators
The three-band \emph{d-p} model is investigated by means of Variational
Monte-Carlo (VMC) method with the BCS-like wave-function supplemented by the
Gutzwiller and Jastrow correlators. The VMC optimization leads to -
superconducting state with a characteristic dome-like shape of the order
parameter for hole doping , in a good agreement with the
experimental observations. Also, the off-diagonal pair-pair correlation
functions, calculated within VMC, vindicates the results obtained very recently
within the diagrammatic expansion of the Gutzwiller wave function method
(DE-GWF) [cf. Phys. Rev. B \textbf{99}, 104511 (2019)]. Subsequently, the
nature of the - pairing is investigated by means of recently proposed
\emph{minimal-size real-space d-wave pairing operators} [Phys. Rev. B
\textbf{100}, 214502 (2019)]. An emergence of the long-range superconducting
ordering for both and orbitals is reported by analysing the
corresponding off-diagonal pair-pair correlation functions. The dominant
character of \emph{d-wave} pairing on orbitals is confirmed. Additionally,
the trial wave-function is used to investigate the magnetic properties of the
system. The analysis of spin-spin correlation functions is carried out and
shows antiferromagnetic , short-range order, as expected.
For the sake of completeness, the charge gap has been estimated, which for the
parent compound takes the value , and
agrees with values reported experimentally for the cuprates
Superconductivity and intra-unit-cell electronic nematic phase in the three-band model of cuprates
The intra-unit-cell nematic phase is studied within the three-band Emery
model of the cuprates with the use of the approach based on the diagrammatic
expansion of the Gutzwiller wave function (DE-GWF). According to our analysis
the spontaneous symmetry breaking of the electronic wave function,
leading to the nematic behavior, can appear due to electron correlations
induced mainly by the onsite Coulomb repulsion, even in the absence of the
corresponding intersite oxygen-oxygen repulsion term. The latter has been
considered as the triggering factor of the nematic state formation in a number
of previous studies. Also, we show that, at the transition to the nematic phase
electron concentration transfer from - to - orbitals takes place, apart
from the usually discussed polarization. The determined stability
regime of the nematic phase appears in the doping range similar to that of the
paired phase, showing that both phases have a common origin, even though they
compete. Also, we show that in a significant doping range a coexistence region
of superconductivity and nematicity appears. The results are discussed in the
view of the experimental findings considering the relation between nematicity
and pseudogap behavior
Superconductivity in the three-band model of cuprates: Variational wave function study and relation to the single-band case
The - superconductivity is analyzed within the three-band -
model with the use of the diagrammatic expansion of the Guztwiller wave
function method (DE-GWF). The determined stability regime of the
superconducting state appears in the range of hole doping , with the optimal doping close to . The pairing
amplitudes between the -orbitals due to copper and orbitals due to
oxygen are analyzed together with the hybrid - pairing. The -
pairing between the nearest neighboring atomic sites leads to the dominant
contribution to the SC phase. Moreover, it is shown that the decrease of both
the Coulomb repulsion on the copper atomic sites () and the charge
transfer energy between the oxygen and copper atomic sites ()
increases the pairing strength as it moves the system from the strong to the
intermediate-correlation regime, where the pairing is maximized. Such a result
is consistent with our analysis of the ratio of changes in the hole content at
the and orbitals due to doping, which, according to experimental study,
increases with the increasing maximal critical temperature [cf. Nat. Commun. 7,
11413 (2016)]. Furthermore, the results for the three-band model are compared
to those for the effective single-band picture and similarities between the two
approaches are discussed. For the sake of completeness, the normal-state
characteristics determined from the DE-GWF approach are compared with those
resulting from the Variational Quantum Monte Carlo method with inter-site
correlations included through the appropriate Jastrow factors