ADVANCED MAGNETIC MATERIALS docx

ADVANCED MAGNETICMATERIALS  EditedbyLeszekMalkinski            Advanced Magnetic Materials Edited by Leszek Malkinski Published by InTech Janeza Trdine 9, 51000 Rijeka, Croatia Copyright © 2012 InTech All chapters are Open Access distributed under the Creative Commons Attribution 3.0 license, which allows users to download, copy and build upon published articles even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. After this work has been published by InTech, authors have the right to republish it, in whole or part, in any publication of which they are the author, and to make other personal use of the work. Any republication, referencing or personal use of the work must explicitly identify the original source. As for readers, this license allows users to download, copy and build upon published chapters even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. Notice Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published chapters. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained in the book. Publishing Process Manager Romina Skomersic Technical Editor Teodora Smiljanic Cover Designer InTech Design Team First published May, 2012 Printed in Croatia A free online edition of this book is available at www.intechopen.com Additional hard copies can be obtained from orders@intechopen.com Advanced Magnetic Materials, Edited by Leszek Malkinski p. cm. ISBN 978-953-51-0637-1    Contents  Preface IX Chapter 1 Rapidly Solidified Magnetic Nanowires and Submicron Wires 1 Tibor-Adrian Óvári, Nicoleta Lupu and Horia Chiriac Chapter 2 M-Type Barium Hexagonal Ferrite Films 33 Mingzhong Wu Chapter 3 Tailoring the Interface Properties of Magnetite for Spintronics 61 Gareth S. Parkinson, Ulrike Diebold, Jinke Tang and Leszek Malkinski Chapter 4 Biomedical Applications of Multiferroic Nanoparticles 89 Armin Kargol, Leszek Malkinski and Gabriel Caruntu Chapter 5 Micro-Fabrication of Planar Inductors for High Frequency DC-DC Power Converters 119 Elias Haddad, Christian Martin, Bruno Allard, Maher Soueidan and Charles Joubert Chapter 6 Fe-Al Alloys’ Magnetism 133 F. Plazaola, E. Apiñaniz, D. Martin Rodriguez, E. Legarra and J. S. Garitaonandia Chapter 7 Magnetic Material Characterization Using an Inverse Problem Approach 171 Ahmed Abouelyazied Abdallh and Luc Dupré Chapter 8 The Everett Integral and Its Analytical Approximation 203 Jenõ Takács    Preface  Recent progress in information technology, wireless communication, biotechnology and microelectronicsrequiresadvanced technologies and newmagnetic materials to meetdemandsofmoderndevices.Thiscollectionofeightchaptersprovidesanup‐to‐ date review of recent trends and developments in technology, characterization methods, theoryandapplicationsofmodernmagneticmaterials withoriginal,never publishedcontributionsfromtherenownedscientistsinthefieldofmagnetism. The bookisaddressedtoadiversegroupofreaderswhichincludestudents,engineersand researchers in the fields of physics, chemistry, bioengineering, electronics and materials science, who wish to enrich their knowledge about advanced magnetics. Depending onthedisciplinerepresented bythereaderstheyareinvitedtoreadentire book or select chapters of particular interest. In order to help with the choice of appropriatechaptersbelowIsummarizetheircontent: Chapter 1. The first chapter reports on fabrication method of amorphous magnetic nanowires with the glass coating using rapid solidification of the melt. The original measurementmethodsandmagneticpropertiesofthenanowireswiththediameters rangingfrom 90nmto13μmarepresented.Inparticular,thearticletargetstheeffect of fabrication conditions and post‐fabrication treatment on mobility and velocity of domain walls  in the nanowires, which can be used in future racetrack memories, magnetic domain wall logic devices, domain wall diodes and oscillators, and other devices. Chapter 2. Future microwavedevicesforwirelesscommunicationsrequire extended frequency range. This chapter treats about new developments in technology and application of a new microwave material‐barium hexagonal ferrite films with extremely high anisotropy, large saturation magnetization and low losses in the microwaverange.Theauthordemonstratesoriginalresultsregardingprototypenotch filtersandphaseshiftersoperatingatmillimeterrangewavelengthswhichemploythe hexagonalferritefilms. Chapter3.Spinelectronics(orspintronics)isanemerging fieldofsciencewhichtakes advantage of magnetic moments to build nonvolatile random access memories and otherdigitaldevices.Inordertocompeteandeventuallyreplacesemiconductor‐based electronics, the spintronic devices must use materials with nearly 100% spin X Preface polarization. The magnetite is one of the best candidates for the spintronic applications. However, its performance in existing devices is drastically reduced by the atomic structure at the surface which differs from that of the bulk. This chapter presentsstudiesofsurface reconstructionofthemagnetiteanddescribesmethodsfor increasing spinefficiencyinspintronicdevicesbypreservingtheFe3O4structureofthe surface. Chapter 4. Multiferroic composites consisting of ferromagnetic and ferroelectric materials provide a unique way of converting magnetic field into electricfield.This processinvolvesstressesattheinterfacebetweenthesematerialsandtakesadvantage ofthepiezoelectricityoftheferroelectricandthemagnetostrictionoftheferromagnetic phase.Thischapterdescribesoriginal methodsofsynthesisofmultiferroiccore‐shell nanoparticles and indicates entirely new biomedical applications of such nanoparticles.Usingexternalalternatingmagneticfieldsitispossibletoproducelocal electricfieldsnearmultiferroicnanoparticleswhichcancontrolopeningandclosingof voltage‐gated ion channels in mammalian  cells. Ion channels are involved in generation and propagation of actionpotentialsin nervesandtheirmalfunctioncan lead to multiple diseases such as cystic fibrosis, diabetes, cardiac arrhythmias, neurological disorders or hypertension.  The proposed mechanism has also potential foranewmethodofcancertreatment. Chapter 5. One of challenges in the design of portable electronic devices is the optimization of on‐chip inductorsfor the powerconversion.This optimization takes intoaccountmultiplefactors,suchassize,achoiceoffabricationsmethod,frequency rangeofoperation,energylossesandcostofthedevice.Thischapterprovidesdetailed discussion about  theory, design, fabrication methods and measurementsof essential parameters characterizing electroplated micro‐inductors for DC‐DC conversion operatingwiththeswitchingfrequencyupto100MHz. Chapter6.Thefocusofthischapterisontherelationbetweenmagneticpropertiesand disorderinthe Fe‐Alsystem.Dependingonthecompositionandthemicrostructure, differentmagneticandstructuralorderscanexistinthissystemincludingaspin‐glass order. Detailed experimental studies based on magnetometry, the Mössbauer effect and X‐raydiffractometry,aswellas theoreticalmodelsofthissystemshow thatthe atomicdisorder,whichcanbecontrolledbya mechanicaltreatmentoranannealing, leadstosignificantincreaseinthelatticeparametersandthemagnetizationcompared tothoseintheordered  structures.Thecontributionofdisordertothemagnetismof thesealloysdependsontheFecontentofthealloyandisthelargestclosetotheequi‐ atomic FeAl alloy, but in Fe75Al25 alloy it is similar to the one given by the volume change. Chapter 7. Direct characterization of the magnetic material parameters based on measurementsofmagneticdeviceswithcomplicatedgeometryisacomplexproblem. This chapter proposes the state‐of‐the‐art methodology to extract materials characteristics from the measurements of electromagnetic devices. This original