Publication Date

Summer 2019

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Physics and Astronomy

Advisor

Ranko Heindl

Keywords

fmr, forc, magnetism, nanowire, reversal, vsm

Subject Areas

Electromagnetics; Nanoscience; Condensed matter physics

Abstract

Magnetic reversal in nickel nanowire arrays due to an axial, external magnetic field was studied through first-order reversal curve (FORC) measurement. A general function modeling the observed Preisach distribution was developed using the moving Preisach model. Fitting allowed determination of the sample's demagnetizing field at saturation and modeling magnetic reversal with respect to the internal magnetic field. Magnetization dynamics in the sample were studied through ferromagnetic resonance (FMR) measurement to aid in interpreting FORC fit results. Combining FORC and FMR results yielded the saturation magnetization and effective demagnetizing factors of the sample. Similar analysis was performed for a thin film sample, indicating an effective magnetizing interaction. The calculated axial demagnetizing factor of the array was significantly larger than the expected value for an isolated nanowire by the ellipsoid approximation. Therefore, this study demonstrates successful quantitative analysis of the demagnetizing interaction between nanowires in the array.

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