pdf, 9 MiB - Infoscience - EPFL
pdf, 9 MiB - Infoscience - EPFL
pdf, 9 MiB - Infoscience - EPFL
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178 CHAPTER 7. CONCLUSION<br />
although the energy gain of the superconducting wavefunction is small, and it is<br />
difficult to get a definitive conclusion on the exact nature of the RVB phase. We<br />
proposed additionally two other models that might shed light on the presence of<br />
orbital currents: (1) We extended first the three-band Hubbard model by considering<br />
the additional out-of-plane apical oxygens and the copper d 3z2−r2 orbitals,<br />
(2) We considered an additional correlated hopping term in the three-band Hubbard<br />
model. In the former model we found interestingly that when the transfer<br />
integrals connected to the apical oxygen are slightly enhanced, then strong orbital<br />
currents start to develop with an in-plane magnetic moment, in agreement<br />
with neutron experimental results. In the latter model, we found that the orbital<br />
currents are strongly stabilized when the correlated hopping V 2 ≈ 0.4. The symmetry<br />
of the current pattern in this case is θ 2 like. Additionally, we have studied<br />
further the orbital current present in the three-band Hubbard model when open<br />
boundaries are considered. In this particular case, the flux flowing through the<br />
boundary is removed, and the charge current phase is still stabilized. Finally,<br />
it has also been argued that holes doped in the antiferromagnetically correlated<br />
spin systems induce incommensurate spin correlations in the ground state for<br />
the one-band hubbard model and three-band model within the mean-field approximation.<br />
Therefore, it would be interesting to compare the energies of these<br />
phases with our Jastrow projected wavefunction, and see if these phases are still<br />
present.