POLYCRYSTALLINE CO-BASED FULL-HEUSLER-ALLOY FILMS FOR SPINTRONIC DEVICES

For the implementation of Heusler-alloy films into next-generation magnetic memories and storages, the optimization of their polycrystalline nature is critical. In this review, we identify two key parameters for the optimization; grain volume for interfacial magnetism and activation volume for magnetic dynamics. We establish correlations between these structural and magnetic volumes and magnetic behavior and then optimize these properties. The optimized polycrystalline films possess exchange bias of 250 Oe induced by low-temperature annealing (400°C for 30 min.), which is induced by the grain volume matching between the Heusler-alloy and antiferromagnetic layers. Despite the matching size measuring 7–8 nm in diameter, the magnetic activation volumes are estimated to be almost 80 nm which is one order of magnitude greater than that for epitaxial films. These values satisfy the requirements for next-generation spintronic device applications and unambiguously prove the great potential of the polycrystalline Heusler-alloy films for future spintronic applications.