Evolution of First-Order Reversal Curves During Self-Assembly of the Co40.2Pt59.8 Nano-Chessboard Structure

The magnetic properties of bulk Co40.2Pt59.8 alloys were investigated during eutectoid decomposition to form the nano-chessboard structure. The nano-chessboard consists of nanorods of the magnetically hard L10 phase coherently embedded in a magnetically soft L12 matrix, with a periodicity on the order of 2540nm. This two-plus-one dimensional structure provides an interesting avenue for investigations into exchange coupling and its effect on permanent magnetic properties in the bulk material. First-order reversal curve measurements, coupled with transmission electron microscopy, show the evolution of the hard phase, characterized by extensive local interactions and the development of strong but incomplete exchange coupling between the hard and soft phases in the nano-chessboard. The soft phase shows evidence of both magnetizing and demagnetizing interactions.