Spontaneous Magnetization in the Disorder dominated Phase of the Twodimensional Random Bond Ising Model

摘要

The selfconsistent approach to the 2D Ising Model with quenched random bondsis extended to the full lattice theory of four real fermions. The additionaldegrees of freedom, neglected in the renormalization-group theory, lead to anew phase between the ferromagnetic and the paramagnetic phase. The disorderaveraged spin-spin correlation function decays exponentially with distance. Thecorresponding correlation length is $1/\eta^2$, where $\eta$ denotes the orderparameter of the new phase introduced by Ziegler.