reorientation of anisotropy in a square well quantum hall sample

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1、ReorientationofAnisotropyinaSquareWellQuantumHallSampleW.Pan1,2,T.Jungwirth3,4,H.L.Stormer5,6,D.C.Tsui1,A.H.MacDonald3,S.M.Girvin3,L.Smrˇcka4,L.N.Pfeiffer5,K.W.Baldwin5,andK.W.West51DepartmentofElectricalEngineering,PrincetonUniversity,Princeton,NewJersey0854

2、42NHMFL,Tallahassee,Florida323103DepartmentofPhysics,IndianaUniversity,Bloomington,Indiana474054InstituteofPhysicsASCR,Cukrovarnick´a10,16200Praha6,CzechRepublic5BellLabs,LucentTechnologies,MurrayHill,NewJersey079746DepartmentofPhysicsandDepartmentofAppliedP

3、hysics,ColumbiaUniversity,NewYork,NewYork10027(February1,2008)Wehavemeasuredmagnetotransportathalf-filledhighLandaulevelsinaquantumwellwithtwooccupiedelectricsubbands.Wefindresistivitiesthatareisotropicinperpendicularmagneticfieldbutbecomestronglyanisotropicatν

4、=9/2and11/2ontiltingthefield.Theanisotropyappears◦atanin-planefield,Bip∼2.5T,withtheeasy-currentdirectionparalleltoBipbutrotatesby90atBip∼10Tandpointsnowinthesamedirectionasinsingle-subbandsamples.Thiscomplexbehaviorisinquantitativeagreementwiththeoreticalcalc

5、ulationsbasedonaunidirectionalchargedensitywavestatemodel.Atwo-dimensional(2D)electrongasisanattractiveparticlestatesinexperimentalsamplegeometries.Forsystemformany-bodyphysicsstudies[1,2].Aparticu-thesampleparametersofthetraditional,single-interfacelarlyric

6、hvarietyofphenomenaassociatedwithstrongspecimensofRefs.[10,11]withasingleelectricsubbandinteractionsamongelectronsappearsintheregimeofoccupied,thetheory[19,20]givesstripesorientedper-thefractionalquantumHalleffect(FQHE)[3,4].Dur-pendiculartothefield,consistent

7、withexperiment.ingmuchofthelastdecade,studiesoftheFQHEhaveAtheoreticalstudy[19]ofUCDWsinparabolicquan-focusedoneven-denominatorLandaulevelfillingfactorstumwellsthathavetwosubbandsoccupiedinzeromag-[5,6]suchasthecompressibleν=1/2stateandtheneticfield,haspredict

8、edmuchmorecomplexbehaviorofν=5/2incompressiblequantumHallfluid.Mostre-theUCDWstate,includingstripestatesinducedbyancently,stronglyanisotropictransporthasbeenobservedin-planefieldandrotationofstrip