Theory for Phase Transitions in Insulating Vanadium Oxide
  We show that the recently proposed S=2 bond model with orbital degrees of freedom for insulating V$_{2}$O$_{3}$ not only explains the anomalous magnetic ordering, but also other mysteries of the magnetic phase transition. The model contains an additional orbital degree of freedom that exhibits a zero temperature quantum phase transtion in the Ising universality class. 
A. Joshi, Michael Ma, F. C. Zhang