First-Order-Reversal-Curve (Forc) Studies of Nanomagnetic Materials

B. Dodrill
Lake Shore Cryotronics,
United States

Keywords: first-order-reversal-curves, FORC, nanoscale magnetic materials


The magnetic characterization of nanoscale materials is usually made by measuring a hysteresis loop. However it is not possible to obtain information of interactions or coercivity distributions from the hysteresis loop alone. Studies of magnetic interactions and magnetization mechanisms at the nanoscale level are of interest not only from a fundamental perspective, but also from a technological perspective because interactions can significantly affect magnetic properties, which in turn impacts their usefulness for technological applications. First-order-reversal-curves (FORCs) are an elegant, nondestructive tool for studying the magnetic properties of materials composed of fine (micron- or nanoscale) magnetic particles. We will discuss the FORC measurement and analysis protocol, and present results for various nanoscale magnetic materials including: • Exchange-coupled nanocomposite permanent magnet materials for which FORC enables differentiation of the magnetically hard and soft phases. • Arrays of magnetic nanowires, nanodots or nanoparticles for which FORC enables investigation of irreversible magnetic interactions or processes in the array due to coupling between adjacent wires, dots or particles. • Exchange-biased magnetic multilayer thin films for which FORC enables one to correlate exchange bias with in-homogeneities existing at the antiferromagnetic/ferromagnetic interface.