Author : Adebanjo Akinwummi Oriade
Publisher : ProQuest
ISBN 13 : 9780549182559
Total Pages : pages
Book Rating : 4.1/5 (825 download)
Book Synopsis Monte Carlo Study of Fluctuations and Magnetization Reversal in Nickel-iron Ferromagnetic Ultra-thin Films by : Adebanjo Akinwummi Oriade
Download or read book Monte Carlo Study of Fluctuations and Magnetization Reversal in Nickel-iron Ferromagnetic Ultra-thin Films written by Adebanjo Akinwummi Oriade and published by ProQuest. This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents a Monte Carlo simulation study of fluctuations and magnetization reversal in thin (5, 10 and 20 nanometers thin), permalloy (Ni 81 Fe 19 films. The study shows how the presence of vertical end pinned domains (VEPDs) in these films leads to nucleation of vortices and anti-vortices. We also show how the vertical edge pinned domains (VEPDs) lead to the formation of horizontal edge pinned domains (HEPDs) in the course of a films magnetization reversal. A mechanism for HEPD-reversal is discovered, involving the creation and motion of a head-to-head domain wall. When vortices nucleate to initiate a films magnetization reversal the switching field varies linearly with temperature, and for reversal that starts with growth of VEPDs switching field has a T 2 dependence. Novel images of spin configuration are used to show fluctuations and magnetization reversal. Our thin film's easy-axis is parallel to the length of the film. For a 5 nm thin film, the author shows that roughness in the edges parallel-to-the-easy-axis increases the switching field of the film in comparison to the switching field of a control film--a similar film with straight edges--by 3.9% in an aspect ratio 5 film and by 6.7% in an aspect ratio 1.5 film. When roughness, or etching, is in the edges perpendicular-to-the-easy-axis the switching field of such films is less than that of the control film by 2.8% and by 4.2% in the respective cases. The mechanisms described in this work are of importance in computer memory and data-storage industry, as well for sensor and circuit isolator applications.