Magnetic Materials: Fundamentals and Applications

290 Pages·1.895 MB·English

by  Nicola A. Spaldin

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MAGNETIC MATERIALS
FundamentalsandApplications
Magnetic Materials is anexcellentintroduction to thebasicsofmagnetism,mag-
neticmaterials,andtheirapplicationsinmoderndevicetechnologies.Retainingthe
concisestyleoftheoriginal,thiseditionhasbeenthoroughlyrevisedtoaddresssig-
nificant developments in the field, including the improved understanding of basic
magneticphenomena,newclassesofmaterials,andchangestodeviceparadigms.
With homework problems, solutions to selected problems, and a detailed list of
references, Magnetic Materials continues to be the ideal book for a one-semester
courseandasaself-studyguideforresearchersnewtothefield.
Newtothisedition:
(cid:2)
Entirelynewchaptersonexchange-biascoupling,multiferroicandmagnetoelectricmate-
rials,andmagneticinsulators
(cid:2)
Revisedthroughout,withsubstantialupdatestothechaptersonmagneticrecordingand
magneticsemiconductors,incorporatingthelatestadvancesinthefield
(cid:2)
Newexampleproblemswithworkedsolutions
nicola a. spaldin is a Professor in the Materials Department at the Univer-
sityofCalifornia,SantaBarbara.Sheisanenthusiasticandeffectiveteacher,with
experience ranging from developing and managing the UCSB Integrative Gradu-
ate Training Program to answering elementary school students’ questions online.
Particularly renowned for her research in multiferroics and magnetoelectrics, her
currentresearchfocusesonusingelectronicstructuremethodstodesignandunder-
stand materials that combine magnetism with additional functionalities. She was
recentlyawardedtheAmericanPhysicalSociety’sMcGroddyPrizeforNewMate-
rials for this work. She is also active in research administration, directing the
UCSB/NationalScienceFoundationInternationalCenterforMaterialsResearch.

MAGNETIC MATERIALS
Fundamentals and Applications
Second edition
NICOLA A. SPALDIN
UniversityofCalifornia,SantaBarbara
CAMBRIDGE UNIVERSITY PRESS
Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore,
São Paulo, Delhi, Dubai, Tokyo
Cambridge University Press
The Edinburgh Building, Cambridge CB2 8RU, UK
Published in the United States of America by Cambridge University Press, New York
www.cambridge.org
Information on this title: www.cambridge.org/9780521886697
© N. Spaldin 2003, 2011
This publication is in copyright. Subject to statutory exception and to the
provision of relevant collective licensing agreements, no reproduction of any part
may take place without the written permission of Cambridge University Press.
First published in print format 2010
ISBN13 9780511900716 eBook (EBL)
ISBN13 9780521886697 Hardback
Cambridge University Press has no responsibility for the persistence or accuracy
of urls for external or thirdparty internet websites referred to in this publication,
and does not guarantee that any content on such websites is, or will remain,
accurate or appropriate.
Magnusmagnesipseestglobusterrestris.
WilliamGilbert,DeMagnete.1600.

Contents
Acknowledgments pagexiii
I Basics
1 Reviewofbasicmagnetostatics 3
1.1 Magneticfield 4
1.1.1 Magneticpoles 4
1.1.2 Magneticflux 6
1.1.3 Circulatingcurrents 6
1.1.4 Ampe`re’scircuitallaw 7
1.1.5 Biot–Savartlaw 8
1.1.6 Fieldfromastraightwire 8
1.2 Magneticmoment 10
1.2.1 Magneticdipole 11
1.3 Definitions 11
Homework 12
2 Magnetizationandmagneticmaterials 14
2.1 Magneticinductionandmagnetization 14
2.2 Fluxdensity 15
2.3 Susceptibilityandpermeability 16
2.4 Hysteresisloops 18
2.5 Definitions 19
2.6 Unitsandconversions 19
Homework 20
3 Atomicoriginsofmagnetism 22
3.1 SolutionoftheSchro¨dingerequationforafreeatom 22
3.1.1 Whatdothequantumnumbersrepresent? 25
3.2 ThenormalZeemaneffect 27
vii
viii Contents
3.3 Electronspin 30
3.4 Extensiontomany-electronatoms 31
3.4.1 Pauliexclusionprinciple 32
3.5 Spin–orbitcoupling 32
3.5.1 Russell–Saunderscoupling 32
3.5.2 Hund’srules 34
3.5.3 jjcoupling 35
3.5.4 TheanomalousZeemaneffect 35
Homework 37
4 Diamagnetism 38
4.1 Observingthediamagneticeffect 38
4.2 Diamagneticsusceptibility 39
4.3 Diamagneticsubstances 41
4.4 Usesofdiamagneticmaterials 42
4.5 Superconductivity 42
4.5.1 TheMeissnereffect 43
4.5.2 Criticalfield 44
4.5.3 Classificationofsuperconductors 44
4.5.4 Superconductingmaterials 44
4.5.5 Applicationsforsuperconductors 46
Homework 46
5 Paramagnetism 48
5.1 Langevintheoryofparamagnetism 49
5.2 TheCurie–Weisslaw 52
5.3 Quenchingoforbitalangularmomentum 54
5.4 Pauliparamagnetism 55
5.4.1 Energybandsinsolids 56
5.4.2 Free-electrontheoryofmetals 58
5.4.3 SusceptibilityofPauliparamagnets 60
5.5 Paramagneticoxygen 62
5.6 Usesofparamagnets 63
Homework 64
6 Interactionsinferromagneticmaterials 65
6.1 Weissmolecularfieldtheory 66
6.1.1 Spontaneousmagnetization 66
6.1.2 Effectoftemperatureonmagnetization 67
6.2 OriginoftheWeissmolecularfield 69
6.2.1 QuantummechanicsoftheHeatom 70
6.3 Collective-electrontheoryofferromagnetism 73
6.3.1 TheSlater–Paulingcurve 76