Microstructures of magnetic nanoscale metallic multilayer and granular alloys with GMR effects

Abstract

AbstractAmong the magnetic metallic multilayer and granular alloys displaying a giant magnetoresistance effect are a wide variety of inhomogeneous magnetic nanostructures. The two characteristic length scales in these systems—spin‐dependent electron mean free path and exchange coupling—vary from a few tens of nanometres to interatomic distances. Advanced methods for the characterization of surface and interface structures have been applied: x‐ray diffraction with a synchrotron radiation source; high‐resolution electron microscopy; field ion microscopy with an atom probe, etc. Some major achievements of research performed mainly at the Institute of Physics, Beijing, are reviewed with an emphasis on the roles of the interface structure and local morphology of nanoscale structures. For example, the structure of the nano‐oxide layers and its physical mechanism in an advanced specular giant magnetoresistance spin valve are characterized. The morphology of the nanoscaled granules has been determined directly in a CuCo granular alloy with giant magnetoresistance effects. The columnar crystallites in the multilayers, which is a very general phenomenon, were confirmed. Copyright © 2004 John Wiley & Sons, Ltd.