Interpretation of Magnetic Force Microscopy Contrast Using Commercially Available Batch Tips for Investigation of Surfac
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FERROMAGNETS of L10 FePd, FePt and CoPt are potentially interesting materials for permanent magnet and data storage applications, due to their large uniaxial magnetocrystalline anisotropies. Consequently, much effort is currently directed toward studying these materials in the form of both thin films and nanoparticles. In bulk form, equiatomic L10 FePd is also an ideal system for fundamental studies of the interplay between microstructure and magnetic domain structure in narrow domain wall (d ~ 11.5 nm) bulk permanent magnets. Through a variety of thermomechanical processing techniques, several characteristic microstructures have been achieved in this system; these microstructures exhibit essentially atomically sharp planar defects with intrinsic coercivities that are highly structure sensitive and that range from 10 to 20 Oe for magnetically soft, single-dominant variant samples,[1] 200 to 500 Oe for conventionally processed polytwinned (PT) samples,[2] 500 to 1400 Oe for combined reaction-processed polycrystalline samples,[3,4] and 2000 to 5000 Oe in nanostructured thin films and powder samples.[5] The L10-type FePd alloys have also served as a suitable P. OHODNICKI and B. WEBLER, Graduate Students formerly with the Materials Science and Engineering Department, University of Pittsburgh, 848 Benedum Hall, O¢Hara Street, Pittsburgh, PA 15261, USA, are with the Materials Science and Engineering Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA. Contact e-mail: [email protected] A. DESHPANDE, Graduate Student and J.M.K. WIEZOREK, Associate Professor, are with the Mechanical Engineering and Materials Science Department, University of Pittsburgh, 848 Benedum Hall, O¢Hara Street, Pittsburgh, PA 15261, USA. Manuscript submitted November 27, 2006. Article published online September 13, 2007. METALLURGICAL AND MATERIALS TRANSACTIONS A
material system for the study of domain wall pinning by planar defects and microstructural heterogeneities[2–5] as well as grain-size effects.[3–5] An understanding of the interplay between the magnetic domain structure and the characteristic microstructural features is required to explain the wide variation in the technical properties observed. One way to provide insight into the nature and extent of the interactions is through direct observation of the domain structure and its correlation with features of the microstructure. In previous studies, the magnetic domain structure in bulk L10 permanent magnets has been investigated using optical and electron microscopy,[2,5–7] as well as simulation techniques.[8] Magnetic force microscopy (MFM) is a relatively new technique that is an attractive alternative because it enables largescale and localized (~10-5 to 10-8 m) investigation, does not require electron transparent regions for imaging, and provides simultaneous high-resolution topographic and magnetic information. For surfaces prepared through electropolishing techniques resulting in some degree of preferential etching, topographic data obtained can also provide info
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