Table Of ContentNoise in Spintronics
Noise in Spintronics
From Understanding to Manipulation
Farkhad G. Aliev
Juan Pedro Cascales
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NoiseinSpintronics:FromUnderstandingtoManipulation
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ISBN978-981-4774-34-5(Hardcover)
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Contents
Preface xi
Acknowledgments xiii
1 Introduction 1
1.1 Magnetoresistance 1
1.1.1 TunnelMagnetoresistance 3
1.2 TunnelingInvolvingMagneticMaterials 4
1.2.1 TheRectangularPotentialBarrier 5
1.2.2 Jullie`reModelforSpin-DependentTunneling 7
1.2.3 CoherentMagneticTunneling 9
1.3 GeneralMotivationbehindNoiseMeasurements
inSpintronics 11
2 NoiseinSpintronicSystems 13
2.1 AFormalDescriptionofNoise 13
2.1.1 StochasticProcesses 13
2.1.2 TimeSeriesAnalysis 16
2.2 WhiteNoise 19
2.2.1 ThermalNoise 19
2.2.2 ShotNoise 19
2.2.3 UnifiedEquationforShotNoiseinTunnel
Junctions 22
2.3 RandomTelegraphNoise 25
2.4 1/f Noise 29
2.4.1 ThermalMagneticFluctuations 33
2.4.2 MagneticNoiseinSpintronics 33
2.5 HighFrequencyNoiseinSpintronics 35
2.5.1 ThermalFerromagneticResonance(T-FMR) 36
vi Contents
2.5.2 ExcessMicrowaveNoiseduetoSpin-Transfer
Torque 37
2.5.3 PhaseNoise 37
3 ExperimentalMethods 41
3.1 AmplifyingtheSignal 42
3.1.1 TheCross-CorrelationTechnique 45
3.2 DataAnalysis 48
3.2.1 1/f NoiseAnalysis 48
3.2.2 ShotNoiseAnalysis 49
3.2.3 RandomTelegraphNoiseAnalysis 51
3.2.3.1 Usingthetimeseriesandspectrum 51
3.2.3.2 Usingonlythetimeseries 51
4 NoiseinMetallicSpinValves 53
4.1 ResistanceLow-FrequencyNoiseinSpinValvesand
ItsRelationwithFluctuation-DissipationTheorem 53
4.2 IsThereExcessLow-FrequencyNoiseintheAPState? 56
4.3 CoupledCurrentandMagnetizationNoise 58
4.4 LinkbetweenDomainWallRelatedNoiseandSpin
TorqueinSpinValvesandSyntheticAntiferromagnets 61
4.5 ShotNoiseinSpinValves 64
5 ShotNoiseinSingle-BarrierMagneticTunnelJunctions 71
5.1 ShotNoiseMTJswithAlO Barriers 71
x
5.2 ShotNoisewithMgOBarriers 75
5.3 Spin-RelatedShotNoise 82
6 Frequency-DependentNoiseinSingle-BarrierMagnetic
TunnelJunctions 89
6.1 1/f NoiseinSingle-BarrierMagneticTunnelJunctions 89
6.1.1 MagneticState-DependentLow-Frequency
NoiseinEpitaxialMagneticTunnelJunctions
withMgO(100)Barriers 92
6.1.2 InterplaybetweenElectronicandMagnetic
Noise 96
6.1.3 DetailedAnalysisoftheLow-FrequencyNoise
intheAPState 96
Contents vii
6.1.4 InfluenceofCarbonDopingonthe
Low-FrequencyNoise 102
6.2 Frequency-DependentSpin-FlipNoisedueto
Non-EquilibriumSpinAccumulation 105
6.2.1 LateralSizeDependenceoftheLow-Frequency
NoiseinSub-MicronMTJs 107
7 InterplaybetweenSpinTorqueandNoiseinSub-100nmSize
MagneticTunnelJunctions 111
7.1 IntroductiontoSpinTorque 111
7.2 TransitionfromT-FMRtoaSteady-StatePrecession 116
7.3 InfluenceofSpinTransferTorqueDynamicson
1/f Noise 121
7.4 STTMagnetizationSwitchingandRandomTelegraph
Noise 125
8 MagnetoresistanceandNoiseinMagneticTunnelJunctions
withOptimizedInterfaceMismatch 131
8.1 LatticeMismatchandInterfacialStressProblems 131
8.2 OptimizationofTunnelingMagnetoresistance
throughImprovedLatticeMismatch 135
8.3 Low-FrequencyNoise 137
8.4 BandEdgeNoiseSpectroscopy 142
8.4.1 GrowthandCharacterizationoftheSamples 144
8.4.2 ExperimentalResults 145
8.4.2.1 BENSmethodandphenomenological
1/f model 149
8.4.3 NumericalCalculations 153
9 NoiseinDouble-BarrierMagneticTunnelJunctions 157
9.1 IntroductiontoDouble-BarrierMagneticTunnel
Junctions 157
9.2 ShotNoiseinDMTJswithTwoFerromagneticLayers 161
9.3 1/f NoiseinDMTJswithThreeFerromagnetic
Electrodes 162
9.4 ConductanceandShotNoiseinEpitaxialDMTJswith
ThreeFerromagneticElectrodes 164
9.4.1 GrowthMethodandJunctionTypes 165
viii Contents
9.4.2 ExperimentalResults 171
9.4.2.1 ControlMTJs 171
9.4.2.2 ShotnoiseinDMTJswithhigh
barrierasymmetry 172
9.4.2.3 DMTJswithlowbarrierasymmetry 173
9.4.2.4 Tunnelingthroughquantumwell
statesinDMTJs 175
9.4.3 TheoreticalModel 177
9.4.3.1 Calculationofshotnoiseinthe
absenceofspinrelaxation 178
9.4.3.2 Calculationofshotnoiseinthe
presenceofspinrelaxation 180
9.4.3.3 Comparisonbetweenexperiment
andtheory 181
9.5 SummaryandPerspectives 183
10 Low-FrequencyNoiseinOrganicElectronicsandSpintronics 185
10.1 SingleMolecularImagingandIdentification
throughtheLow-FrequencyNoise 186
10.2 OrganicResistiveSwitchingMemories 192
10.3 Low-FrequencyNoiseinOrganicElectronics 193
10.4 Low-FrequencyNoiseRelatedwithMolecules
Bending 195
10.5 PhononsExcitationModifiedShotNoisein
MolecularElectronics 199
10.6 ElectronTransportandNoiseinOrganic
Spintronics 201
10.6.1 IntroductiontoOrganicSpintronics 201
10.6.2 OrganicMagneticTunnelJunctionsinthe
ElectronTunnelingRegime 203
10.6.2.1 Samplegrowth 203
10.6.2.2 Super-Poissonianshotnoise 207
10.6.2.3 Modelanddiscussionofthe
results 209
10.6.3 SequentialTunnelingthroughThick
OrganicLayersOrganicSpintronics:
ConductanceandNoise 214
Contents ix
10.6.3.1 Growthandsample
characteristics 214
10.6.3.2 Suppressedshotnoiseinthe
variable-rangehoppingregime 217
10.7 PossibilityofPhononNoiseSpectroscopyin
OrganicSpintronicDevices 219
11 ElectronTransportandNoiseinSmallDotsConnectedto
FerromagneticLeads 221
11.1 BriefIntroductioninCoulombBlockade 222
11.2 TheoreticalConsiderationsofShotNoisein
FM/QD/FMStructures 224
11.3 ElectronTransportandNoiseinFM/QD/FMin
thePresenceofKondoEffect 226
11.4 ShotNoiseinFM/QD/FMinthePresenceof
KondoEffect 229
11.5 ShotNoiseinFM/QD/FMinthePresenceof
Co-Tunneling 231
11.6 MultiterminalandDoubleQuantumDots
ConnectedtoFerromagneticLeads 233
11.7 ConcludingRemarksandOpenProblems 237
12 ChargeandSpinTransportandNoiseinTwo-Dimensional
Materials 239
12.1 NoiseinGraphene 241
12.1.1 AnIntroductiontographene 241
12.1.1.1 Obtaininggraphene 242
12.1.1.2 Crystalstructureofgraphene 243
12.1.1.3 Electronicbandstructureof
graphene 244
12.1.2 TransportPropertiesofGraphenearound
theDiracPoint 246
12.1.3 1/f NoiseinGraphene 246
12.1.4 ShotNoiseinGraphene 249
12.2 Low-FrequencyNoiseinSingle/Few-Layer
TransitionMetalDichalcogenides 251
12.3 Outlook:Spin-RelatedNoisein2DElectronics 253
