Investigators: R. D. McMichael, L. H. Bennett, M. J. Donahue, D. E. Mathews, H. J. Brown

Technical Description:

A wide variety of complementary techniques are brought together to study the details of magnetic structures and magnetization processes in metals. For example, surface magnetic structures can be imaged directly with techniques such as magnetic force microscopy (MFM) and the magnetic indicator film technique (MOIF). Interpretation of such images and extrapolation to interior structures can be accomplished with micromagnetic modeling, which uses bulk magnetic measurements (VSM and Barkhausen signal measurements) as auxiliary inputs.

Technical Objectives:

• Accurately determine microstructural defects affecting both magnetic and material properties.

• Develop an understanding of the role of manufacturing processes on magnetic properties.

• Image dynamic magnetization behavior, e.g., Barkhausen effect and magnetic creep.

• Develop micromagnetic computer codes with experimental verification.

• Perform experiments and computer simulations on the influence of metallic structures on magnetic field distributions surrounding the structures.

Anticipated Outcome:

• Improved performance of commercial magnetic recording devices and sensors.

• More accurate micromagnetic models as a result of better input data and experimental verification.

• Standardization of MFM and MOIF techniques.

• Improved database of magnetic material properties.

• Improved magnetic resonance imaging (MRI).

Accomplishments for FY 1995:

• Successful MOIF and MFM imaging of magnetization processes and structures in thin films and multilayers.

• Development of a 2D micromagnetic code applicable to thin film studies.

• Modeling of metallic parts in large applied fields led to the recognition that part geometry and eddy currents are particularly important factors controlling artifacts in MRI.

Impacts and Technical Highlights:

• MOIF and MFM results provide an initial benchmark against which future work can be compared.

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Last modified: Mon Jan 06 09:46:15 1997 Metallurgy Webmeister