First order magnetic transition in CeFe${}_2$ alloys: Phase-coexistence and metastability

First order ferromagnetic (FM) to antiferromagnetic (AFM) phase transition in doped-CeFe${}_2$ alloys is studied with micro-Hall probe technique. Clear visual evidence of magnetic phase-coexistence on micrometer scales and the evolution of this phase-coexistence as a function of temperature, magnetic field and time across the first order FM-AFM transition is presented. Such phase-coexistence and metastability arise as natural consequence of an intrinsic disorder-influenced first order transition. Generality of this phenomena involving other classes of materials is discussed.