Topological order in an entangled SU(2) ⊗ XY spin-orbital ring.
We present rigorous topological order which emerges in a one-dimensional spin-orbital model due to the ring topology. Although this model with SU(2) spin and XY orbital interactions is known to exactly separate spins from orbitals by means of a unitary transformation on the open chain, we find that they are not quite independent when the chain is closed, and the spins form two half-rings carrying opposite quasimomenta. We show that on changing the topology from an open to a periodic chain, the degeneracy of the ground state is partially lifted while the low-energy excitations have a quadratic dispersion as a function of the total quasimomentum. This novel type of topological order which emerges from changing the topology from an open to a periodic chain is reminiscent of the infinite-U Hubbard chain.
Marian Smoluchowski Institute of Physics, Jagellonian University, Reymonta 4, PL-30059 Kraków, Poland.
Wojciech
W
Brzezicki
Marian Smoluchowski Institute of Physics, Jagellonian University, Reymonta 4, PL-30059 Kraków, Poland.
Jacek
J
Dziarmaga
Marian Smoluchowski Institute of Physics, Jagellonian University, Reymonta 4, PL-30059 Kraków, Poland and Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany.
Andrzej M
AM
Oleś