Research Abstract


Absence of a Spin Liquid Phase in the Hubbard Model on the Honeycomb Lattice

2012年12月18日 Scientific Reports 2 : 992 doi: 10.1038/srep00992


Sandro Sorella1, 2, 3, 大塚 雄一3 & 柚木 清司3, 4, 5

  1. イタリア国際高等研究所(SISSA)
  2. CNR-IOM デモクリトス・シミュレーション・センター(イタリア)
  3. 独立行政法人 理化学研究所 計算科学研究機構 量子系物質科学研究チーム
  4. 独立行政法人 理化学研究所 基幹研究所 柚木計算物性物理研究室
  5. 独立行政法人 科学技術振興機構 戦略的創造研究推進事業(JST-CREST)
A spin liquid is a novel quantum state of matter with no conventional order parameter where a finite charge gap exists even though the 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 (SM) and an antiferromagnetic insulator (AFMI). 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, if any, a very weak evidence of this spin liquid region. Instead, our calculations strongly indicate a direct and continuous quantum phase transition between SM and AFMI.