Date of Graduation

Spring 2018

Degree

Master of Science in Materials Science

Department

Physics, Astronomy, and Materials Science

Committee Chair

Robert Mayanovic

Keywords

epitaxy, magnetocrystalline anisotropy, perpendicular exchange bias, iron platinum, high density recording media, magnetic random access memory

Subject Categories

Condensed Matter Physics | Engineering Physics | Plasma and Beam Physics

Abstract

Perpendicular exchange bias (PEB), particularly when it persists in nanomaterials to room temperature, is highly useful for applications in spintronic devices and for advancing the development of high-information-density magnetic random access memory. A complete mechanistic and theoretical understanding of exchange bias has evaded scientists. The quest to discover novel materials for magnetic and spintronic device applications has stimulated investigation into nanomaterials having optimal and/or tailored magnetic properties that are based on the exchange bias effect. In this study, pulsed laser deposition was used to grow epitaxial PEB systems of ferromagnetic FePt thin film layers that are interfaced with antiferromagnetic NiO thin film layers. Different phases of FePt were grown on a single crystal MgO substrate and overlain with NiO in order to investigate the exchange bias effect between the two magnetic layers. The magnetic ordering and spin-spin interactions at the FePt-NiO thin film interface results in the orthogonal/perpendicular exchange bias due to the magnetocrystalline anisotropy of FePt and orientation of the NiO antiferromagnetic planes. Using XRD, TEM, HAADF imaging, and TEM-FFT analyses, it was determined that the FePt and NiO layers were grown epitaxially on the (100) surface of the MgO substrate. HAADF imaging and TEM-EDS confirm the thin films have minimal diffusion between the layers. SQUID magnetometry data measured from the thin film samples in both in-plane and out-of-plane orientations show that the chemical ordered L10 FePt exhibits PEB effects.

Copyright

© Zachary B. Leuty

Open Access

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