凝聚态物理前沿讲座_方忠_Quantum Simulation in the F

方忠中国科学院物理研究所，理论室QuantumSimulationintheFieldofSpintronicsandOrbitronicsAcknowledgement:Y.G.Yao,K.TerakuraN.NagaosaY.Tokura凝聚态物理前沿讲座Contents1.QuantumsimulationsbasedonDFT(1)Simpleintroductiontofirst-principlescalculations(2)Ourmethod,code,andcomputerfacilities2.Dissipationlessquantumcurrentforspintronics(1)AnomalousHallEffect(2)SpinHallCurrent(3)AnomalousNernstEffect3.OrbitonandOrbitronics(1)PhasediagramofLa1-xSrxMnO3(2)Orbital-dependentphasecontrolinCa2-xSrxRuO4(3)Magnetismindoubleperovskites4.Surfaceoftransition-metaloxidesQuantumSimulationbasedonDFTAtoms+electronsElectronsMany-bodyElectronsSingle-particleDensityFunctionalAdiabaticApproximationHohenberg-KohnKohn-ShamHellmann-FeynmanForceandStressMDSCFSelf-consistentSolverforKSproblemSCFLDAGGALDA+ULDA+UmethodPseudopotentialSchemeNormal-conservingPseudopotentialUltra-SoftPseudopotentialVirtualCrystalApproxmation(VCA)ForvirtualatomsSolveSchrodingerequationIonicunscreenedpotentialHowtosolvethesingleparticleproblemRealSpace(noFFT)FiniteelementFinitedifferenceMulti-gridAdaptiveWavelet…ReciprocalSpace(withFFT)LACOLMTOFLAPWPAWPlane-waveGreen’sfunction…Pseudopotential,ASA,…OtherProblemsinSimulationsExchange-correlationfunctionalStrongly-correlatedsystemsForcecalculation&MoleculardynamicsMagnetic,optical&electronicpropertiesExcitedStatesNon-equilibrium&Time-dependentprocessOrder(N)method&LargescaleCatalysis,Chemicalreaction,Bio-systems…First-principlescalculationsbasedonDFTPlane-wavebasisUltra-softPseudo-potentialLDA,GGA,LDA+U,etc…Virtualcrystalapproximation(VCA)RealspaceRMMforlargersystemsFullparallelizationbyMPISGI,IBM-SP,Alpha,Cray,VPP,PC-ClusterOurMethodSTATECode:(SimulationalToolforAtomTechnology)MainContributors:Z.Fang,Y.Morikawa,T.Ikeda,H.SawadaandotherJRCATmembersFordetails:Z.Fang,et.al,J.Phys:Cond.Matt.,14,3001(2001).(reviewarticle)～100,000lines,Accuracy～1meV/Atom,～200atoms.WidelyusedinJapan,Taiwan,Korea,Denmark,etc.IBMSP690,64CPUs,128G,1T-diskThreeCharactersofElectronChargeSpinOrbitalwellknown“hot”topicnewExtensivelyusedbeingusedwillbeusedI,V,ρ……ChargecurrentChargeexcitationspinwaveorbitonChargecurrentspincurrentmovement……anisotropyfunctionality….SpintronicsTheelectronhasbothchargeandspin.Mostlyonlythechargepropertyisused.Energyscaleforthechargeinteractionishigh,~1eV,energyscaleforthespininteractionislow,~10-100meV.Muchlowerpowerconsumptionforspin-baseddevice.Spin-basedelectronicsalsopromisesagreaterintegrationbetweenthelogicandstoragedevicesProblemsforSpintronicdevicesspininjectionintosemiconductorOhmicinjectionfromferromagnetLowefficiency(Difficulty):Ferromagneticmetal:conductivitymismatchspinpolarizationisalmostlostatinterface.Ferromagneticsemiconductor(e.g.Ga1-xMnxAs):Curietemperaturemuchlowerthanroomtemp.Ferromagnetictunneljunction.spindetectionbyferromagnetspintransportinsemiconductorspinrelaxationtimeOpticalpumpandprobeOnlytwoknownexamplesofdissipationlesstransportinsolids!Supercurrentinasuperconductorisdissipationless,sinceLondonequationrelatedJtoA,nottoE!Vectorpotential=oddunderT,chargecurrent=oddunderT.IntheQHE,theHallconductivityisproportionaltothemagneticfieldB,whichisoddunderT.Laughlinargument:allstatesbelowthefermienergycontributetotheHallconductance.Stredaformula,TKNNformularelatestheHallconductancetothe1stChernnumber.Newdissipationlesstransportinsolidsduetospin-orbitalcoupling!☺AnomalousHallEffect(chargecurrent):[1]T.Jungwirth,et.al.,PRL,88,207208(2002);[2]Z.Fang,et.al,SCIENCE,302,92(2003)][3]Y.G.Yao,et.al,PRL,92,37204(2004);[4]W.L.Lee,et.al,SCIENCE,303,1647(2003)]Conventional:ρxy=R0H+4πRSMIntrinsicMechanism:σxyσxy(M)ThusJx=σxyEyisTinvariantJisodd,Eiseven,Misodd☺DissipationlessspinHallcurrent:[1]S.Murakami,et.al,SCIENCE,301,1348(2003);[2]J.E.Hirsch,et.al.,PRL,83,1834(1999)[3]J.Sinova,et.al,PRL,92,126603(2004)[4]S.Q.Shen,et.al.,cond-mat/040305.[5]Y.Xiong&X.C.Xie,cond-mat/0403083.SpincurrentisevenunderTBjHFMjAHEConventionalHallAnomalousHallEESpinjSHEESpinHallMeritofAHEandSHE1.Itworksbecauseofspin-orbitalcoupling,whichisactiveevenatroomT.2.Itisentirelytopological(dissipationless).Spin-OrbitalCouplingBerryPhaseMagneticMonopolesinMomentumSpaceAnomalousHallcurrentandSpinHallcurrent(Botharedissipationless)IntrinsicMechanismEffectiveHamiltonianforadiabatictransportEquationofmotion(Diracmonopole)DriftvelocityTopologicaltermNontrivialspindynamicscomesfromtheDiracmonopoleatthecenterofkspace,witheg=l:Adiabatictransport=potentialVdoesnotcauseinter-bandtransitionsonlyretaintheintra-bandmatrixelementsFullQuantumCalculationsBasedonKuboFormularAnomalousHallconductivitywithSpinHallconductivityJysConservedSpinCurrent(S.Murakami,et.al.,cond-mat/0310005)Conservedspinwhichsatisfydefinecurrenti,n,m=bandindexα,β,γ=kramersdoubletsindexZ.Fang,et.al.,SCIENCE302,92(2003)反常Hall效应与动量空间中的磁单极CalculatedGaugeFluxforkz=0inSrRuO3bz(kz=0)GMMMMZ.Fang,et.al,SCIENCE,302,92(2003)SrRuO3SrRuO3CalculatedSpinHallCurrentinGaAsCalculatedSpinCurrentforGaAsandSnTeOneExampleforHalf-MetalMnAsFullyspinpolarizedanomalousHallcurrentinMnAsSpinconductivityAHEconductivityAnomalousNernstEffectBVFMVConventionalAnomalousInverseAnomalousNernstEffect:CoolingandrefrigeratorFMHeatcurrentjQExHeatcurrent:Eq.ofmotion:egt2g3z2-r2x2-y2xyyzzxOrbitronicsOrbitalDegreesofFreedom(ODF)EnergyDownspinUpspinEFO-2pO-2pt2gt2gegeg2-fold(ODF)3-fold“Half-metal”VariousOrderingsFMA-typeC-typeG-typeLatticeSpinChargeOrbitalSC,TMR,CMR,M-ITransition,AnomalousHallEffect,Magneto-optical,Ferroelectricity,Piezoelectricity,etc…ExperimentalTheoreticalSCIENCE288,462(2000).J.Phys.Soc.Jap.68,3790(1999).PhaseDiagramofTetragonalLa1-xSrxMnO3(ControllingofOrbitalandSpinOrderings)Z.Fang&K.Terakura,PRL84,3169(2000).FMA-AFC-AFG-AFOrbitalandSpinOrderingsPhysics:SpinOrbitalLatticeDoubleexchangeSuper-exchangeCompressionLessconductivityElectric-Field-inducedOrbitalSwitchingK.Hatsuda,APL83,3329(2003).LatticeSpinChargeOrbitalElectronicStructuresofCa2-xSrxRuO4EnergyDownspinUpspinEFO-2pO-2pt2gt2gegeg3-foldCa2-xSrxRuO4:IsovalentsubstitutionRotationRotationRotation++TiltingTilting+CompressionAFMottInsulatorNearlyFMMetalS.Nakatsuji,etal.,PRLO.Friedt,etal.,PRBIssues:(1)Howtounderstandthecomplicatedphasediagram.(2)What’stheruleoforbital.EffectsofStructureDistortionsZ.Fang&K.Terakura,PRB64,R20509(2001)RotationxyorbitalVHSFMTiltingyz,zxnestingAFOccupationsandMagnetizationsZ.Fangetal.PRB(2004).OrbitalPhaseDiagramofCa2-xSrxRuO4CaSrDopingx0.00.20.52.0EEfxyyz,zxEEfxyyz,zxEEfxyyz,zxxyxyferro-orbitalorderingAF,S=1fromyz,zxFM,S=1/2fromxyItinerantyz,zxwithsmallSNMstateWithVHSfromxy1.J.H.Jung,Z.Fang,et.al.,PRL91,056403(2003).2.Z.Fang,et.al.,PRB69,045116(2004).[110]RuO6八面体在 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 面的旋转Sr2RuO4的表面电子结构LEEDSTM1.R.Matzdorf,Z.Fang,et.al.,SCIENCE289,746(2000).2.Z.Fang,et.al.,PRB64,R20509(2001)PDOSofvariousdopingxExp.XASCalculatedXAS90K300KOpticalconductivityExperimentsCalculationsJ.H.Jung,Z.Fang,etal.PRL(2003).FeFeMSr2FeMO6(M=Mo,W,Re)8ÅWhyTcissohighforM=Mo,Re?WhyM=WcaseisAFinsulator?EFdstatesdstatesMajorityspinMinorityspinModstateorotherpstatesFMZ.Fang,et.al.,PRB63,R180407(2001)EFdstatesdstatesMajorityspinMinorityspinModstatesorotherpstatesAFNewMechanismforSr2FeMO6and(Ga1-xMnx)AsFe(t2g)SpinEFM(t2g)(M=Mo,Re)Fe(t2g)ElectronicStructureofSr2FeMoO6SurfaceofSrTiO3withOxygenVacancyImportantsubstrateSurfacegassensitivityFerroelectricityCatalyticallyactiveSTMSTST.Kubo,et.al.,PRL86,1801(2001)H.Tanaka,et.al.,Jpn.J.Appl.Phys.32,1405(1993)StructureChargeMagnetizationSrOTiO2SrTiOLDA+USurfaceofSrTiO3withoxygenvacancy(Spinpolarizedsurface)Z.Fang,et.al.,Surf.Sci.Lett.470,L75(2001)SrOtermination(GGA)TiO2termination(GGA)26°26°26°TiO2termination(LDA+U)5x5STMofSrTiO3surface[100][100][001][001]SurfaceCentral（La,Sr)OterminationMnO2terminationMnOrbitalpolarizationonthesurfacesofLa1-xSrxMnO3Z.Fang,et.al.,J.Phys.Soc.Jpn.70,3356(2001).SummaryQuantumSimulationChargeSpinOrbital(Electronics)(Spintronics)(Orbitronics)Problems:1.Efficientmethodforcross-correlatedsystems2.Towardslargescale(surface&interface)3.Accuratemethodformany-bodysystems