First Order Magnetic Transition in Doped CeFe₂ Alloys: Phase Coexistence and Metastability

First order ferromagnetic (FM) to antiferromagnetic (AFM) phase transition in doped CeFe₂ alloys is studied with the 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 a natural consequence of an intrinsic disorder-influenced first order transition. The generality of these phenomena involving other classes of materials is discussed.