We have formulated an auxiliary-boson mean-field theory consistent with the SU(2) symmetry of the Heisenberg model. At half filling, we find an infinite number of solutions related by the symmetry. Away from half filling the kinetic energy, acting as a symmetry-breaking field, selects a superconducting state of d-wave symmetry. The mean-field theory describes bosons and fermions with finite kinetic energy close to half filling. We derive self-consistent equations for the superconducting transition temperature Tc. We find that Tc vanishes at large and small filling factors.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics