Sign phase transition and directed paths in random media
Spivak В., Feng S., Zeng F.
We consider в lattice model which corresponds to the high temperature expansions of disordered Ising and Heisenberg models and to the deeply localized regime of the disordered Anderson model. The spin correlation functions for the Ising and Heisenberg model and the amplitude of electron tunneling for the Anderson model exhibit a "sign phase transition". At small concentration ζ of scatterers with a negative scattering amplitude these quantities have predictable signs while at large ζ their signs are unpredictable. PACS: 05.20.-y, 82.20.-w