Pseudo-spin dynamical symmetry

J. P. Wallington, James F. Annett

We present a hidden SU(2) ‘pseudo-spin’ symmetry of the half-filled Hubbard model, relating superconducting and charge orderings. Using an appropriate functional integral representation, we show the consequences of this symmetry for the quasiparticle excitation spectrum.

V. Pažma, Peter Prešnajder

Roman Boča

Zhi-Fang Xu, Yuki Kawaguchi, Li You +1 more

We develop a symmetry classification scheme to find ground states of pseudo-spin-$\frac{1}{2}$, spin-1, and spin-2 spin-orbit-coupled spinor Bose-Einstein condensates and show that as the SO(2) symmetry of simultaneous spin and space rotations is broken into discrete cyclic groups, various types of lattice structures emerge in the absence of a lattice potential. Examples include two different kagome lattices for pseudo-spin-$\frac{1}{2}$ condensates and a nematic vortex lattice in which uniaxial and biaxial spin textures align alternatively for spin-2 condensates. For the pseudo-spin-$\frac{1}{2}$ system, although mean-field states always break time-reversal symmetry, there exists a time-reversal invariant many-body ground state, which is fragmented and expected to be observed in a microcondensate.

O. Tjernberg

The application of spin, pseudo spin and space group symmetry to find symmetry adapted states for the square planar Hubbard model is discussed. An approach based on pseudo spin configurations and the application of Young tableaux to the permutation group is presented. The method is illustrated for the case of a 4*4 cluster and the complete classification of the states for this cluster is given. It is shown that the linear dimension of the largest matrix block is reduced by three orders of magnitude by application of the above symmetries.

Monique Combescure, Didier Robert