433 research outputs found
High Temperature Superconductivity from Strong Correlation
It is important to understand the mechanism of high-temperature
superconductivity. It is obvious that the interaction with large energy scale
is responsible for high critical temperature . The Coulomb interaction is
one of candidates that bring about high-temperature superconductivity because
its characteristic energy is of the order of eV. There have been many works for
the Hubbard model including three-band d-p model with the on-site Coulomb
repulsion to investigate a possibility of high-temperature superconductivity.
It is, of course, not trivial whether the on-site Coulomb interaction leads to
a pairing interaction between two electrons. We argue that high-temperature
superconductivity is possible in the strongly correlated region by using the
variational Monte Carlo method for the two-dimensional t-U-J-V model. The
exchange interaction J and the nearest-neighbour attractive interaction V
cooperate with U and will act to enhance the critical temperature.Comment: in Proceedings of International Symposium on Superconductivity 201
Mott transition in cuprate high-temperature superconductors
In this study, we investigate the metal-insulator transition of charge
transfer type in high-temperature cuprates. We first show that we must
introduce a new band parameter in the three-band d-p model to reproduce the
Fermi surface of high temperature cuprates such as BSCCO, YBCO and Hg1201. We
present a new wave function of a Mott insulator based on the improved
Gutzwiller function, and show that there is a transition from a metal to a
charge-transfer insulator for such parameters by using the variational Monte
Carlo method. This transition occurs when the level difference
between d and p orbitals reaches a
critical value . The energy gain , measured from the
limit of large , is proportional to for
: . We
obtain using the realistic band parameters
- β¦