The impact of ageing on the magnetic properties of Cu(OH)2 nanoribbons

We report a comparative study of structural, morphological and magnetic properties of freshly prepared and aged Cu(OH)2 nanoribbons. Microscopy studies, performed with a transmission electron microscope, a scanning electron microscope and an atomic force m

INSTITUTEOFPHYSICSPUBLISHINGNanotechnology16(2005)1623–1629

NANOTECHNOLOGY

doi:10.1088/0957-4484/16/9/037

TheimpactofageingonthemagneticpropertiesofCu(OH)2nanoribbons

1ˇPolonaUmek1,2,AndrejZorko1,PavelCevc1,MihaSkarabot,

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ZvonkoJagliˇciˇc,JinWonSeo,L´aszloForr´o,HansvanTool,LouisClaudeCBrunel4andDenisArˇcon1,5

JoˇzefStefanInstitute,Jamova39,1000Ljubljana,Slovenia

InstituteofPhysicsofComplexMatter,FSB,EPFL,1015Lausanne,Switzerland3

InstitutofMathematics,PhysicsandMechanics,Jadranska19,Ljubljana,Slovenia4

NationalHighMagneticFieldLaboratory,FloridaStateUniversity,Tallahassee,FL32310,USA5

FacultyforMathematicsandPhysics,Jadranska19,Ljubljana,Slovenia

2

1

E-mail:polona.umek@ijs.si

Received31March2005,in nalform1June2005Published1July2005

Onlineatstacks.iop.org/Nano/16/1623

Abstract

Wereportacomparativestudyofstructural,morphologicalandmagneticpropertiesoffreshlypreparedandagedCu(OH)2nanoribbons.Microscopystudies,performedwithatransmissionelectronmicroscope,ascanningelectronmicroscopeandanatomicforcemicroscope,demonstratethattheaveragelengthoftheCu(OH)2nanoribbonsdecreaseswithageing.ThebasicCu(OH)2structureis,however,stillpreservedatthisstage,as

con rmedbyx-raydiffractionmeasurements.Morphologicalchangesarere ectedalsointhemagneticproperties.Forinstance,wefoundthatCu(OH)2nanoribbonswithageinggraduallylosetheirone-dimensionalantiferromagneticcharacterasthedefects,whichformduringtheageingprocess,tendtocuttheCu–(OH)2–Cuchainsintoincreasinglyshorter

segments.Thesedefectsinagedsamplescompletelychangethespectrumofmagneticexcitationsandmakeagedsamplesmuchmorethree-dimensionalfromthepointofviewofmagnetism.

1.Introduction

One-dimensional(1D)semiconductingandmetallicnanos-tructureswillrepresentthekeyelementsforthenextgenerationofelectronicandmagneticdevices.Besidescarbonnanotubes,whichareconsideredasthemostpromisingmaterial[1–3],nanowires,nanotubesandnanorodscanbegrownfromotherinorganiclayeredmaterialsaswell.Forinstance,nanowirearraysweregrownfromCo[4],In2O3[5]orMo6S3I6[6].Amongstthemostinterestingnanostructuresformicroelec-tronicsarecopperandcopper-basednanostructures.However,tooursurprisewefoundonlyafewattemptsintheliteraturetogrowcopper[7–10]orcopper(II)-based[7,11–15]nanos-tructures,althoughonewouldexpectthatcontrolledgrowthofCuorCuOnanostructureswould ndtheirplaceinelectronicdevicesalmostimmediately.

Onepossiblestartingpointtodesigncopperandcopper-basednanostructurescouldbecopper(II)hydroxide,

0957-4484/05/091623+07$30.00©2005IOPPublishingLtd

(Cu(OH)2).Cu(OH)2isalayeredmaterialanditsgrowthrateisthelargestalongtheCu–(OH)2–Cuchains[16].Therefore,itispossibletogrowsmallCu(OH)2nanocrystalswithaveryhighaspectratiobetweenthelengthandthediameter.

Cu(OH)2isalsoaveryinterestingmaterialfromthepointofmagnetism,sincetheCuionsareintheCu2+(S=1/2)oxidationstate.Itsmagneticpropertiesareextremelysensitivetothepresenceofdifferentanionsandstructuraldetails[17–19].Basically,theCu(OH)2structureconsistsofCu–(OH)2–CuchainsconnectedbyanotherCu–(OH)2–Culinkintoaquasi-layeredstructure.ThelayersareconnectedviahydrogenbondsofthetypeOH···O.TheCu2+ionthus ndsitselftrappedinanoxygenoctahedralenvironment[20,21],whichisstronglydistorted.TheCu2+ionisdisplacedfromtheequatorialplaneoftheoctahedronby0.134Å.TheCu–Odistancesare1.948and1.972Åintheequatorialplane.Thenext-nearestCu–Odistanceis2.356Å[20].Assumingoctahedralcoordination,thenextvertexdistanceis2.915Å.

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