2017/09/18 by A. M. Belemuk, N. M. Chtchelkatchev, A. V. Mikheyenkov +2
Physics and Astronomy · #Boson #Cold Atom Physics and Bose-Einstein Condensates #Condensed matter physics #Fermion #Ground state #Hamiltonian (control theory) #Hubbard model #Phase (matter) #Phase diagram #Physics #Physics of Superconductivity and Magnetism #Quantum #Quantum many-body systems #Quantum mechanics #Quantum phase transition #Quantum phases #Spin (aerodynamics) #Superconductivity #cond-mat.mes-hall #cond-mat.quant-gas #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.96.094435
8 pages, 9 figures (in press), Phys. Rev. B, 2017
arxiv created 2017/09/18 · openalex created_date 2017/09/25 · openalex publication_date 2017/09/27 · arxiv updated 2017/09/28 · openalex updated_date 2026/08/05
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.