Ferromagnet to spin glass transition in 2d Ising models

With random bonds of both signs, the classical two-dimensional Ising model undergoes a ferromagnet-to-paramagnet transition at low temperatures which is still little understood. The transition is governed by a zero-temperature fixed point separating ferromagnetic and spin-glass ground states. We use efficient evaluation of ground states of large systems to numerically study the critical behavior. To more fully characterize the transition we utilize free-fermionic representations of the renormalization group flows in the vicinity of the critical point, and point out possible connections with quantum infinite-randomness physics.