Magnetic phase diagram and quantum phase transitions in a two-species boson model
Abstract
We analyze the possible types of ordering in a boson-fermion model. The Hamiltonian is inherently related to the Bose-Hubbard model for vector two-species bosons in optical lattices. We show that such a model can be reduced to the Kugel-Khomskii type spin-pseudospin model, but in contrast to the usual version of the latter model, we are dealing here with the case of spin S =1 and pseudospin 1 /2 . We show that the interplay of spin and pseudospin degrees of freedom leads to a rather nontrivial magnetic phase diagram including the spin-nematic configurations. Tuning the spin-channel interaction parameter Us gives rise to quantum phase transitions. We find that the ground state of the system always has the pseudospin domain structure. On the other hand, the sign change of Us switches the spin arrangement of the ground state within domains from a ferro- to antiferromagnetic one. Finally, we revisit the spin (pseudospin)-1/2 Kugel-Khomskii model and see the inverse picture of phase transitions.
- Publication:
-
Physical Review B
- Pub Date:
- September 2017
- DOI:
- 10.1103/PhysRevB.96.094435
- arXiv:
- arXiv:1709.05816
- Bibcode:
- 2017PhRvB..96i4435B
- Keywords:
-
- Condensed Matter - Strongly Correlated Electrons;
- Condensed Matter - Mesoscale and Nanoscale Physics;
- Condensed Matter - Quantum Gases
- E-Print:
- 8 pages, 9 figures (in press), Phys. Rev. B, 2017