Superconductivity:AVeryShortIntroduction VERYSHORTINTRODUCTIONSareforanyonewantingastimulating andaccessiblewayintoanewsubject.Theyarewrittenbyexperts,andhave beenpublishedinmorethan25languagesworldwide. Theseriesbeganin1995,andnowrepresentsawidevarietyoftopicsin history,philosophy,religion,science,andthehumanities.TheVSIlibrary nowcontains200volumes—aVeryShortIntroductiontoeverythingfrom ancientEgyptandIndianphilosophytoconceptualartandcosmology—and willcontinuetogrowtoalibraryofaround300titles. VeryShortIntroductionsavailablenow: AFRICANHISTORY CHAOS LeonardSmith JohnParkerandRichardRathbone CHOICETHEORY MichaelAllingham AMERICANPOLITICALPARTIES CHRISTIANART BethWilliamson ANDELECTIONS L.SandyMaisel CHRISTIANITY LindaWoodhead THEAMERICANPRESIDENCY Citizenship RichardBellamy CharlesO.Jones CLASSICALMYTHOLOGY ANARCHISM ColinWard HelenMorales ANCIENTEGYPT IanShaw CLASSICS ANCIENTPHILOSOPHY JuliaAnnas MaryBeardandJohnHenderson ANCIENTWARFARE CLAUSEWITZ MichaelHoward HarrySidebottom THECOLDWAR RobertMcMahon ANGLICANISM MarkChapman CONSCIOUSNESS THEANGLO-SAXONAGE JohnBlair SusanBlackmore ANIMALRIGHTS DavidDeGrazia CONTEMPORARYART ANTISEMITISM StevenBeller JulianStallabrass TheApocryphalGospels PaulFoster CONTINENTALPHILOSOPHY ARCHAEOLOGY PaulBahn SimonCritchley ARCHITECTURE AndrewBallantyne COSMOLOGY PeterColes ARISTOTLE JonathanBarnes THECRUSADES ChristopherTyerman ARTHISTORY DanaArnold CRYPTOGRAPHY ARTTHEORY CynthiaFreeland FredPiperandSeanMurphy THEHISTORYOFASTRONOMY DADAANDSURREALISM MichaelHoskin DavidHopkins ATHEISM JulianBaggini DARWIN JonathanHoward AUGUSTINE HenryChadwick THEDEADSEASCROLLS Autism UtaFrith TimothyLim BARTHES JonathanCuller DEMOCRACY BernardCrick BESTSELLERS JohnSutherland DESCARTES TomSorell THEBIBLE JohnRiches DESIGN JohnHeskett THEBRAIN MichaelO’Shea DINOSAURS DavidNorman BRITISHPOLITICS AnthonyWright DOCUMENTARYFILM BUDDHA MichaelCarrithers PatriciaAufderheide BUDDHISM DamienKeown DREAMING J.AllanHobson BUDDHISTETHICS DamienKeown DRUGS LeslieIversen CAPITALISM JamesFulcher THEEARTH MartinRedfern CATHOLICISM GeraldO’Collins ECONOMICS ParthaDasgupta THECELTS BarryCunliffe EGYPTIANMYTH GeraldinePinch EIGHTEENTH-CENTURYBRITAIN HUMANRIGHTS AndrewClapham PaulLangford HUME A.J.Ayer THEELEMENTS PhilipBall IDEOLOGY MichaelFreeden EMOTION DylanEvans INDIANPHILOSOPHY SueHamilton EMPIRE StephenHowe INTELLIGENCE IanJ.Deary ENGELS TerrellCarver INTERNATIONALMIGRATION ETHICS SimonBlackburn KhalidKoser THEEUROPEANUNION INTERNATIONALRELATIONS JohnPinderandSimonUsherwood PaulWilkinson EVOLUTION ISLAM MaliseRuthven BrianandDeborahCharlesworth JOURNALISM IanHargreaves EXISTENTIALISM ThomasFlynn JUDAISM NormanSolomon FASCISM KevinPassmore JUNG AnthonyStevens FEMINISM MargaretWalters KABBALAH JosephDan THEFIRSTWORLDWAR KAFKA RitchieRobertson MichaelHoward KANT RogerScruton FOSSILS KeithThomson KIERKEGAARD PatrickGardiner FOUCAULT GaryGutting THEKORAN MichaelCook FREEWILL ThomasPink law RaymondWacks FREESPEECH NigelWarburton Lincoln AllenC.Guelzo THEFRENCHREVOLUTION LINGUISTICS PeterMatthews WilliamDoyle LITERARYTHEORY JonathanCuller FREUD AnthonyStorr LOCKE JohnDunn FUNDAMENTALISM MaliseRuthven LOGIC GrahamPriest galaxies JohnGribbin MACHIAVELLI QuentinSkinner GALILEO StillmanDrake THEMARQUISDESADE JohnPhillips GAMETHEORY KenBinmore MARX PeterSinger GANDHI BhikhuParekh MATHEMATICS TimothyGowers Geography Themeaningoflife JohnMatthewsandDavidHerbert TerryEagleton GEOPOLITICS KlausDodds MEDICALETHICS TonyHope GERMANLITERATURE MEDIEVALBRITAIN NicholasBoyle JohnGillinghamandRalphA.Griffiths GLOBALCATASTROPHES Memory JonathanK.Foster BillMcGuire MODERNART DavidCottington GLOBALWARMING MarkMaslin MODERNCHINA RanaMitter GLOBALIZATION ManfredSteger MODERNIRELAND SeniaPaˇseta THEGREATDEPRESSIONANDTHE ModernJapan NEWDEAL EricRauchway ChristopherGoto-Jones HABERMAS JamesGordonFinlayson MOLECULES PhilipBall HEGEL PeterSinger Mormonism HEIDEGGER MichaelInwood RichardLymanBushman HIEROGLYPHS PenelopeWilson MUSIC NicholasCook HINDUISM KimKnott MYTH RobertA.Segal HISTORY JohnH.Arnold NATIONALISM StevenGrosby TheHistoryofLife MichaelBenton nelsonmandela EllekeBoehmer HistoryofMedicine THENEWTESTAMENTAS WilliamBynum LITERATURE KyleKeefer THEHISTORYOFTIME Leofranc NEWTON RobertIliffe Holford-Strevens NIETZSCHE MichaelTanner HIV/AIDS AlanWhiteside NINETEENTH-CENTURY HOBBES RichardTuck BRITAIN ChristopherHarvie HUMANEVOLUTION BernardWood andH.C.G.Matthew NORTHERNIRELAND ROUSSEAU RobertWokler MarcMulholland RUSSELL A.C.Grayling Nothing FrankClose RUSSIANLITERATURE nuclearweapons CatrionaKelly JosephM.Siracusa THERUSSIANREVOLUTION THEOLDTESTAMENT S.A.Smith MichaelD.Coogan SCHIZOPHRENIA PARTICLEPHYSICS FrankClose ChrisFrithandEveJohnstone PAUL E.P.Sanders SCHOPENHAUER PHILOSOPHY EdwardCraig ChristopherJanaway PHILOSOPHYOFLAW Scienceandreligion RaymondWacks ThomasDixon PHILOSOPHYOFSCIENCE Scotland RabHouston SamirOkasha Sexuality Ve´roniqueMottier PHOTOGRAPHY SteveEdwards SHAKESPEARE GermaineGreer PLATO JuliaAnnas SIKHISM EleanorNesbitt POLITICALPHILOSOPHY SOCIALANDCULTURAL DavidMiller ANTHROPOLOGY POLITICS KennethMinogue JohnMonaghanandPeterJust POSTCOLONIALISM RobertYoung SOCIALISM MichaelNewman POSTMODERNISM SOCIOLOGY SteveBruce ChristopherButler SOCRATES C.C.W.Taylor POSTSTRUCTURALISM THESPANISHCIVILWAR CatherineBelsey HelenGraham PREHISTORY ChrisGosden SPINOZA RogerScruton PRESOCRATICPHILOSOPHY Statistics DavidJ.Hand CatherineOsborne STUARTBRITAIN JohnMorrill PSYCHIATRY TomBurns Superconductivity PSYCHOLOGY GillianButlerand StephenBlundell FredaMcManus TERRORISM CharlesTownshend THEQUAKERS PinkDandelion THEOLOGY DavidF.Ford QUANTUMTHEORY TRAGEDY AdrianPoole JohnPolkinghorne THETUDORS JohnGuy RACISM AliRattansi TWENTIETH-CENTURY THERENAISSANCE JerryBrotton BRITAIN KennethO.Morgan RENAISSANCEART TheunitedNations GeraldineA.Johnson JussiM.Hanhim¨aki relativity RussellStannard THEVIKINGS JulianRichards ReligioninAmerica WITTGENSTEIN A.C.Grayling TimothyBeal WORLDMUSIC PhilipBohlman ROMANBRITAIN PeterSalway THEWORLDTRADE THEROMANEMPIRE ORGANIZATION ChristopherKelly AmritaNarlikar Availablesoon: biography HermioneLee WritingandScript Puritanism FrancisJ.Bremer AndrewRobinson sovietunion StephenLovell Communism LeslieHolmes Fashion RebeccaArnold Formoreinformationvisitourwebsite www.oup.co.uk/general/vsi/ Stephen Blundell Superconductivity A Very Short Introduction 3 3 GreatClarendonStreet,Oxfordox26dp OxfordUniversityPressisadepartmentoftheUniversityofOxford. ItfurtherstheUniversity’sobjectiveofexcellenceinresearch,scholarship, andeducationbypublishingworldwidein Oxford NewYork Auckland CapeTown DaresSalaam HongKong Karachi KualaLumpur Madrid Melbourne MexicoCity Nairobi NewDelhi Shanghai Taipei Toronto Withofficesin Argentina Austria Brazil Chile CzechRepublic France Greece Guatemala Hungary Italy Japan Poland Portugal Singapore SouthKorea Switzerland Thailand Turkey Ukraine Vietnam OxfordisaregisteredtrademarkofOxfordUniversityPress intheUKandincertainothercountries PublishedintheUnitedStates byOxfordUniversityPressInc.,NewYork #StephenBlundell2009 Themoralrightsoftheauthorhavebeenasserted DatabaserightOxfordUniversityPress(maker) Firstpublished2009 Allrightsreserved.Nopartofthispublicationmaybereproduced, storedinaretrievalsystem,ortransmitted,inanyformorbyanymeans, withoutthepriorpermissioninwritingofOxfordUniversityPress, orasexpresslypermittedbylaw,orundertermsagreedwiththeappropriate reprographicsrightsorganization.Enquiriesconcerningreproduction outsidethescopeoftheaboveshouldbesenttotheRightsDepartment, OxfordUniversityPress,attheaddressabove Youmustnotcirculatethisbookinanyotherbindingorcover andyoumustimposethesameconditiononanyacquirer BritishLibraryCataloguinginPublicationData Dataavailable LibraryofCongressCataloginginPublicationData Dataavailable TypesetbySPIPublisherServices,Pondicherry,India PrintedinGreatBritainby AshfordColourPressLtd,Gosport,Hampshire ISBN 978–0–19–954090–7 1 3 5 7 9 10 8 6 4 2 To Sam, Maria, and Victoria This page intentionally left blank Contents Acknowledgements xi Listofillustrations xiii 1 Whatissuperconductivity? 1 2 Thequestforlowtemperatures 7 3 Thediscoveryofsuperconductivity 20 4 Expulsion 30 5 Pairingup 48 6 Symmetry 66 7 Beforethebreakthrough 84 8 High-temperaturesuperconductivity 95 9 Themakingofthenewsuperconductors 109 10 Whathavesuperconductorseverdoneforus? 128 Dramatispersonae 141 Furtherreading 145 Index 147