Ferromagnetic response of a high-temperature quantum antiferromagnet

Article

关键词: MEAN-FIELD THEORY;    INTERACTING FERMI GAS;    HUBBARD-MODEL;    OPTICAL LATTICE;    MOTT INSULATOR;    MONTE-CARLO;    ULTRACOLD ATOMS;    TRANSITION;    SUPERFLUID;    PHASE;   

DOI  :  10.1103/PhysRevB.89.121118

来源: SCIE

【 摘 要 】

We study the finite-temperature antiferromagnetic phase of the ionic Hubbard model in the strongly interacting limit using quantum Monte Carlo based dynamical mean-field theory. We find that the ionic potential plays a dual role in determining the antiferromagnetic order. A small ionic potential (compared to Hubbard repulsion) increases the superexchange coupling in the projected sector of the model, leading to an increase in the Ned temperature of the system. A large ionic potential leads to resonance between projected antiferromagnetically ordered configurations and density ordered configurations with double occupancies, thereby killing antiferromagnetism in the system. This novel way of degrading antiferromagnetism leads to spin polarization of the low-energy single-particle density of states. The dynamic response of the system thus mimics ferromagnetic behavior, although the system is still an antiferromagnet in terms of the static spin order.

【 授权许可】

Free