QuantumSimulationintheFieldofSpintronicsandOrbitronics凝聚態物理前沿講座ppt課件

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-metaloxidesppt課件QuantumSimulationbasedonDFTAtoms+electronsElectronsMany-bodyElectronsSingle-particleDensityFunctionalAdiabaticApproximationHohenberg-KohnKohn-ShamHellmann-FeynmanForceandStressMDSCFppt課件Self-consistentSolverforKSproblemSCFLDAGGALDA+Uppt課件LDA+Umethodppt課件PseudopotentialSchemeNormal-conservingPseudopotentialUltra-SoftPseudopotentialppt課件VirtualCrystalApproxmation(VCA)ForvirtualatomsSolveSchrodingerequationIonicunscreenedpotentialppt課件HowtosolvethesingleparticleproblemRealSpace(noFFT)FiniteelementFinitedifferenceMulti-gridAdaptiveWavelet…ReciprocalSpace(withFFT)LACOLMTOFLAPWPAWPlane-waveGreen’sfunction…Pseudopotential,ASA,…ppt課件OtherProblemsinSimulationsExchange-correlationfunctionalStrongly-correlatedsystemsForcecalculation&MoleculardynamicsMagnetic,optical&electronicpropertiesExcitedStatesNon-equilibrium&Time-dependentprocessOrder(N)method&LargescaleCatalysis,Chemicalreaction,Bio-systems…ppt課件First-principlescalculationsbasedonDFTPlane-wavebasisUltra-softPseudo-potentialLDA,GGA,LDA+U,etc…Virtualcrystalapproximation(VCA)RealspaceRMMforlargersystemsFullparallelizationbyMPI

SGI,IBM-SP,Alpha,Cray,VPP,PC-ClusterOurMethodppt課件

STATECode:

(Simulational

ToolforAtomTechnology) MainContributors:

Z.Fang, Y.Morikawa,T.Ikeda,H.Sawada andotherJRCATmembers

Fordetails:

Z.Fang,et.al,J.Phys:Cond.Matt.,14,3001(2001). (reviewarticle)

～100,000lines,Accuracy～1meV/Atom,

～200atoms.WidelyusedinJapan,Taiwan,Korea,Denmark,etc.ppt課件IBMSP690,64CPUs,128G,1T-diskppt課件ThreeCharactersofElectron

ChargeSpinOrbitalwellknown“hot”topicnewExtensivelyusedbeingusedwillbeusedI,V,ρ

…

…ChargecurrentChargeexcitationspinwaveorbitonChargecurrentspincurrentmovement…

…anisotropyfunctionality

….ppt課件SpintronicsTheelectronhasbothchargeandspin.Mostlyonlythechargepropertyisused.

Energyscaleforthechargeinteractionishigh,~1eV,

energyscaleforthespininteractionislow,~10-100meV.

Muchlowerpowerconsumptionforspin-baseddevice.

Spin-basedelectronicsalsopromisesagreaterintegrationbetweenthelogicandstoragedevicesppt課件ProblemsforSpintronicdevices

spininjectionintosemiconductor

Ohmicinjectionfromferromagnet

Lowefficiency(Difficulty):Ferromagneticmetal:conductivitymismatch

spinpolarizationisalmostlostatinterface.Ferromagneticsemiconductor(e.g.Ga1-xMnxAs):Curietemperaturemuchlowerthanroomtemp.Ferromagnetictunneljunction.

spindetectionbyferromagnet

spintransportinsemiconductorspinrelaxationtimeOpticalpumpandprobeppt課件Onlytwoknownexamplesofdissipationlesstransportinsolids!

Supercurrentinasuperconductorisdissipationless,sinceLondonequationrelatedJtoA,nottoE!Vectorpotential=oddunderT,chargecurrent=oddunderT.

IntheQHE,theHallconductivityisproportionaltothemagneticfieldB,whichisoddunderT.Laughlinargument:allstatesbelowthefermienergycontributetotheHallconductance.Stredaformula,TKNNformularelatestheHallconductancetothe1stChernnumber.

ppt課件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+4πRSM

IntrinsicMechanism:σxyσxy(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.SpincurrentisevenunderTppt課件BjHFMjAHEConventionalHallAnomalousHallEESpinjSHEESpinHallppt課件MeritofAHEandSHE1.Itworksbecauseofspin-orbitalcoupling,whichisactiveevenatroomT.2.Itisentirelytopological(dissipationless).ppt課件Spin-OrbitalCouplingBerryPhaseMagneticMonopolesinMomentumSpaceAnomalousHallcurrentandSpinHallcurrent(Botharedissipationless)IntrinsicMechanismppt課件EffectiveHamiltonianforadiabatictransportEquationofmotion(Diracmonopole)DriftvelocityTopologicaltermNontrivialspindynamicscomesfromtheDiracmonopoleatthecenterofkspace,witheg=l:Adiabatictransport=potentialVdoesnotcauseinter-bandtransitions

onlyretaintheintra-bandmatrixelementsppt課件FullQuantumCalculationsBasedonKuboFormularAnomalousHallconductivitywithSpinHallconductivityJysppt課件ConservedSpinCurrent(S.Murakami,et.al.,cond-mat/0310005)Conservedspinwhichsatisfydefinecurrenti,n,m=bandindexα,β,γ

=kramersdoubletsindexppt課件Z.Fang,et.al.,SCIENCE302,92(2003)反常Hall效應與動量空間中的磁單極ppt課件CalculatedGaugeFluxforkz=0inSrRuO3bz(kz=0)GMMMMZ.Fang,et.al,SCIENCE,302,92(2003)ppt課件SrRuO3ppt課件SrRuO3ppt課件CalculatedSpinHallCurrentinGaAsppt課件CalculatedSpinCurrentforGaAsandSnTeppt課件OneExampleforHalf-MetalMnAsppt課件FullyspinpolarizedanomalousHallcurrentinMnAsSpinconductivityAHEconductivityppt課件AnomalousNernstEffectBVFMVConventionalAnomalousppt課件InverseAnomalousNernstEffect:CoolingandrefrigeratorFMHeatcurrentjQExHeatcurrent:Eq.ofmotion:ppt課件egt2g3z2-r2x2-y2xyyzzxOrbitronicsppt課件OrbitalDegreesofFreedom(ODF)EnergyDownspinUpspinEFO-2pO-2pt2gt2gegeg2-fold(ODF)3-fold“Half-metal”ppt課件VariousOrderingsFMA-typeC-typeG-typeLatticeSpinChargeOrbitalSC,TMR,CMR,M-ITransition,AnomalousHallEffect,Magneto-optical,Ferroelectricity,Piezoelectricity,etc…ppt課件ExperimentalTheoreticalSCIENCE

288,462(2000).J.Phys.Soc.Jap.

68,3790(1999).PhaseDiagramofTetragonalLa1-xSrxMnO3(ControllingofOrbitalandSpinOrderings)Z.Fang&K.Terakura,PRL84,3169(2000).ppt課件FMA-AFC-AFG-AFOrbitalandSpinOrderingsPhysics:SpinOrbitalLatticeDoubleexchangeSuper-exchangeCompressionLessconductivityppt課件Electric-Field-inducedOrbitalSwitchingK.Hatsuda,APL83,3329(2003).ppt課件LatticeSpinChargeOrbitalElectronicStructuresofCa2-xSrxRuO4EnergyDownspinUpspinEFO-2pO-2pt2gt2gegeg3-foldppt課件Ca2-xSrxRuO4:IsovalentsubstitutionRotationRotationRotation++TiltingTilting+CompressionAFMottInsulatorNearlyFMMetalS.Nakatsuji,etal.,PRLO.Friedt,etal.,PRBppt課件Issues:(1)Howtounderstandthecomplicatedphasediagram.(2)What’stheruleoforbital.ppt課件EffectsofStructureDistortionsZ.Fang&K.Terakura,PRB64,R20509(2001)RotationxyorbitalVHSFMTiltingyz,zxnestingAFppt課件OccupationsandMagnetizationsZ.Fangetal.PRB

(2004).ppt課件OrbitalPhaseDiagramofCa2-xSrxRuO4CaSrDopingx0.00.20.52.0EEfxyyz,zxEEfxyyz,zxEEfxyyz,zxxyxyferro-orbitalorderingAF,S=1fromyz,zxFM,S=1/2fromxyItinerantyz,zxwithsmallSNMstateWithVHSfromxy1.J.H.Jung,

Z.Fang,et.al.,

PRL

91,056403(2003).2.Z.Fang,et.al.,PRB69,045116(2004).ppt課件[110]RuO6

八面體在表面的旋轉Sr2RuO4的表面電子結構LEEDSTM1.R.Matzdorf,

Z.Fang,et.al.,

SCIENCE

289,746(2000).2.Z.Fang,et.al.,PRB64,R20509(2001)ppt課件PDOSofvariousdopingxppt課件Exp.XASCalculatedXAS90K300Kppt課件OpticalconductivityExperimentsCalculationsJ.H.Jung,Z.Fang,etal.PRL(2003).ppt課件FeFeMSr2FeMO6(M=Mo,W,Re)8?WhyTcissohighforM=Mo,Re?WhyM=WcaseisAFinsulator?ppt課件EFdstatesdstatesMajorityspinMinorityspinModstateorotherpstatesFMZ.Fang,et.al.,PRB63,R180407(2001)EFdstatesdstatesMajorityspinMinorityspinModstatesorotherpstatesAFNewMechanismforSr2FeMO6and(Ga1-xMnx)Asppt課件Fe(t2g)SpinEFM(t2g)(M=Mo,Re)Fe(t2g)ElectronicStructu