Sandro Sorella, Yuichi Otsuka, Seiji Yunoki
A spin liquid is a novel quantum state of matter where a finite charge gap exists although the conventional band theory would predict metallic behavior. Finding a stable spin liquid in two or higher spatial dimensions is one of the most challenging and debated issues in condensed matter physics. Very recently, it has been reported that a model of graphene, i.e., the Hubbard model on the honeycomb lattice, can show a spin liquid ground state in a wide region of the phase diagram, between a semi-metal and an antiferromagnetic insulating phase. Here, by performing numerically exact quantum Monte Carlo simulations, we extend the previous study to much larger clusters (containing up to 2592 sites), and find no evidence of this spin liquid region. Our calculations together with previously established results strongly indicate that it is possible to establish a spin liquid ground state only in different models with real frustration.
View original:
http://arxiv.org/abs/1207.1783
No comments:
Post a Comment