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70RANDOMWALKTOGRAPHENENobelLecture,December8,2010byANDREK.GEIMSchoolofPhysicsandAstronomy,TheUniversityofManchester,OxfordRoad,ManchesterM139PL,UnitedKingdom.Ifonewantstounderstandthebeautifulphysicsofgraphene,theywillbespoiledforchoicewithsomanyreviewsandpopularsciencearticlesnowavailable.IhopethatthereaderwillexcusemeifonthisoccasionIrecommendmyownwritings[1–3].Insteadofrepeatingmyselfhere,IhavechosentodescribemytwistyscientificroadthateventuallyledtotheNobelPrize.Mostpartsofthisstoryarenotdescribedanywhereelse,anditstime-linecoverstheperiodfrommyPhDin1987tothemomentwhenour2004paper,recognisedbytheNobelCommittee,wasacceptedforpublication.Thestorynaturallygetsdenserineventsandexplanationstowardstheend.Also,itprovidesadetailedreviewofpre-2004literatureand,withthebenefitofhindsight,attemptstoanalysewhygraphenehasattractedsomuchinter-est.Ihavetriedmybesttomakethisarticlenotonlyinformativebutalsoeasytoread,evenfornon-physicists.ZOMBIEMANAGEMENTMyPhDthesiswascalled“Investigationofmechanismsoftransportrelaxa-tioninmetalsbyaheliconresonancemethod”.AllIcansayisthatthestuffwasasinterestingatthattimeasitsoundstothereadertoday.Ipublishedfivejournalpapersandfinishedthethesisinfiveyears,theofficialdurationforaPhDatmyinstitution,theInstituteofSolidStatePhysics.WebofScienceso-berlyrevealsthatthepaperswerecitedtwice,byco-authorsonly.ThesubjectwasdeadadecadebeforeIevenstartedmyPhD.However,everycloudhasitssilverlining,andwhatIuniquelylearnedfromthatexperiencewasthatIshouldnevertortureresearchstudentsbyofferingthem“zombie”projects.AftermyPhD,IworkedasastaffscientistattheInstituteofMicro-electronicsTechnology,Chernogolovka,whichbelongstotheRussianAcademyofSciences.TheSovietsystemallowedandevenencouragedjuniorstafftochoosetheirownlineofresearch.Afterayearofpokingindifferentdirections,Iseparatedresearch-wisefrommyformerPhDsupervisor,VictorPetrashov,andstarteddevelopingmyownniche.Itwasanexperimentalsystemthatwasbothnewanddoable,whichwasnearlyanoxymoron,takingintoaccountthescarceresourcesavailableatthetimeatSovietresearchAndreGeim_lect_s70_95.indd22011-08-2908:48:4671institutes.Ifabricatedasandwichconsistingofathinmetalfilmandasuper-conductorseparatedbyathininsulator.Thesuperconductorservedonlytocondenseanexternalmagneticfieldintoanarrayofvortices,andthishighlyinhomogeneousmagneticfieldwasprojectedontothefilmunderinvestiga-tion.Electrontransportinsuchamicroscopicallyinhomogeneousfield(varyingonasubmicronscale)wasnewresearchterritory,andIpublishedthefirstexperimentalreportonthesubject[4],whichwascloselyfollowedbyanindependentpaperfromSimonBending[5].Itwasaninterestingandreasonablyimportantniche,andIcontinuedstudyingthesubjectforthenextfewyears,includingaspellattheUniversityofBathin1991asapostdoctoralresearcherworkingwithSimon.Thisexperiencetaughtmeanimportantlesson:thatintroducinganewexperimentalsystemisgenerallymorerewardingthantryingtofindnewphenomenawithincrowdedareas.Thechancesofsuccessaremuchhigherwherethefieldisnew.Ofcourse,thefantasticresultsoneoriginallyhopesforareunlikelytomaterialise,but,intheprocessofstudyinganynewsystem,somethingoriginalinevitablyshowsup.ONEMAN’SJUNK,ANOTHERMAN’SGOLDIn1990,thankstoVitalyAristov,directorofmyInstituteinChernogolovkaatthetime,IreceivedasixmonthvisitingfellowshipfromtheBritishRoyalSociety.LaurenceEavesandPeterMainfromNottinghamUniversitykindlyagreedtoacceptmeasavisitor.Sixmonthsisaveryshortperiodforexperimentalwork,andcircumstancesdictatedthatIcouldonlystudyde-vicesreadilyavailableinthehostlaboratory.AvailableweresubmicronGaAswiresleftoverfrompreviousexperiments,alldoneanddustedafewyearsearlier.Underthecircumstances,myexperienceofworkinginapoverty-strickenSovietacademywashelpful.Thesamplesthatmyhostsconsideredpracticallyexhaustedlookedlikeagoldveintome,andIstartedworking100hoursperweektoexploitit.ThisshortvisitledtotwoPhys.Rev.Lettersofdecentquality[6,7],andIoftenusethisexperiencetoteasemyyoungercolleagues.Whenthingsdonotgoasplannedandpeoplestartcomplaining,Iprovokethembyproclaiming‘thereisnosuchthingasbadsamples;thereareonlybadpostdocs/students’.Searchcarefullyandyouwillalwaysfindsomethingnew.Ofcourse,itisbettertoavoidsuchexperiencesandexplorenewterritories,butevenifoneisfortunateenoughtofindanexperimentalsystemasnewandexcitingasgraphene,meticulousnessandperseveranceallowonetoprogressmuchfurther.ThepaceofresearchatNottinghamwassorelentlessand,atthesametimesoinspiring,thatareturntoRussiawasnotanoption.SwimmingthroughSoviettreacleseemednolessthanwastingtherestofmylife.Soattheageofthirty-threeandwithanh-indexof1(latestpapersnotyetpublished),IenteredtheWesternjobmarketforpostdocs.DuringthenextfouryearsImovedbetweendifferentuniversities,fromNottinghamtoCopenhagentoBathandbacktoNottingham.EachmoveallowedmetogetacquaintedwithAndreGeim_lect_s70_95.indd32011-08-2908:48:4672yetanothertopicortwo,significantlybroadeningmyresearchhorizons.ThephysicsIstudiedinthoseyearscouldbebroadlydescribedasmesoscopicandinvolvedsuchsystemsandphenomenaastwo-dimensionalelectrongases(2DEGs),quantumpointcontacts,resonanttunnellingandthe