Disorder-driven phase transitions and domain fragmentation
The Random Field Ising Model (RFIM) adds quenched random fields h_i ~ N(0,Δ²) to each site.
Imry-Ma argument (1975): in d≤2, any disorder Δ>0 destroys long-range order at T=0. In d=3, a phase transition survives.
Disorder fragments ordered domains into a complex mosaic. The critical exponents are non-mean-field and still debated.
Bright = spin up (+1), Dark = spin down (−1). Colors show disorder field magnitude.