Kaleidoscope of exotic quantum phases in a frustrated XY model
  The existence of quantum spin liquids was first conjectured by Pomeranchuk some 70 years ago, who argued that frustration in simple antiferromagnetic theories could result in a Fermi-liquid-like state for spinon excitations. Here we show that a simple quantum spin model on a honeycomb lattice hosts the long sought for Bose metal with a clearly identifiable Bose surface. The complete phase diagram of the model is determined via exact diagonalization and is shown to include four distinct phases separated by three quantum phase transitions. 
Christopher N. Varney, Kai Sun, Victor Galitski, and Marcos Rigol
cond-mat.str-el cond-mat.quant-gas