2 research outputs found
Theory of electrons with orbital degeneracy
The Hubbard model for electrons with orbital degeneracy is shown to have an
underlying SU_d(4) symmetry of spin-orbital double. A hidden charge SU_c(4)
symmetry is exposed and an extended Lieb-Mattis transformation which maps these
two symmetries into each other is given. On the basis of elementary degenerate
perturbative theory, it is shown that the system with strong repulsive coupling
is equivalent to a SO(6) Heisenberg magnet at half-filling and a SU(4) one at
quarter-filling. The band is half-filled at all temperature for . The
features of ground state and low-lying excitations in one dimension are
indicated according to exact solutions. Various possibilities of symmetry
breaking are also given.Comment: Extended PRB version, 6 pages, symmetry breaking adde