Entropy as a function of magnetization for a 2D spin-ice model   exhibiting a Kasteleyn transition
  We present a combined analytical and numerical study of the entropy as a function of magnetization for an orientable 2D spin-ice model that exhibits a Kasteleyn transition. The model that we use is related to the well known six-vertex model but, as we show, our representation of it is more convenient for constructing approximate expressions for the entropy at fixed magnetization. We also discuss directions for further work, including the possibility of deforming our model into one exhibiting a quantum Kasteleyn transition. 
S. A. Grigera and C. A. Hooley
cond-mat.str-el cond-mat.stat-mech