On Proximity of 4/7 Solid Phase of 3He Adsorbed on Graphite -Origin of   Specific-Heat Anomalies in Hole-Doped Density-Ordered Solid-
  We theoretically study the stability of the solidified second-layer 3He at 4/7 of the first-layer density adsorbed on graphite, which exhibits quantum spin liquid. We construct a lattice model for the second-layer 3He by taking account of density fluctuations on the third layer together by employing the refined configuration recently found by path integral Monte Carlo simulations. When holes are doped into the 4/7 solid, within the mean-field approximation, the density-ordered fluid emerges. The evolution of hole pockets offers a unified explanation for the measured doping and temperature dependences of specific-heat anomalies. We argue that differentiation in momentum space is a key to understanding the physics and accounts for multiscale thermodynamic anomalies in the mono- and double-layered 3He systems beyond the mean-field level. 
Shinji Watanabe, Masatoshi Imada