More than three decades since the discovery of high-temperature superconductivity in ceramic cuprate materials, the study of electronic states in cuprate materials to promote understanding of the superconducting phase and related phenomena has become incredibly important.
In a new paper published in Art EPJ BErnesto Raposa of the Federal University of Pernambuco, Brazil, and his co-authors consider one of the essential physical properties of cuprate superconducting compounds, the pseudogap, which describes the state when the Fermi material surface has a partial energy gap. .
Despite impressive progress in the study of cuprate superconducting compounds, the authors note that researchers have not yet reached a consensus on the physical origin of the pseudo-discontinuity phase in these compounds.
To solve this problem, the team uses the Hubbard single-band Hamiltonian to interact with neighboring electrons on CuO2-planes of cuprate systems to study the occurrence of the pseudogap phase.
In addition to examining the usual Coulomb repulsion energy in place and the jumps of electrons to nearby neighboring sites, the researchers also examined the competing mechanism of jumps to nearby neighboring sites.
To conduct the study, the team doped the system with electrons or holes to approximate critical doping concentrations at which the pseudogap closes in addition to estimating the range of concentrations in which it is maintained.
Using a model created to display the connection parameters of cuprate La2CuO4the team found critical concentrations of doping electrons and holes, and obtained a charge transfer gap and maximum pseudogap energy.
The authors say that the pseudogap does not open when the next adjacent kinetic energy is canceled, describing this conclusion as remarkable.
The researchers’ calculations show that the energy of the jump to the next neighbor corresponds to the value of the observed pseudogap in the experimental measure in cuprate systems.
This suggests that competing electron jumps in the nodal directions of the Brillouin zone may play a role in the occurrence of the pseudogap phase in cuprate materials.