Spintronics M1 Nano
18 pages

Spintronics M1 Nano

-

Le téléchargement nécessite un accès à la bibliothèque YouScribe
Tout savoir sur nos offres

Description

Niveau: Supérieur, Master, Bac+4
Spintronics M1-Nano 1 Chapter V: spintronics • Magnetism and itinerant magnetism •Giant magnetoresistance •Hard disks magnetic heads •Spin valve effect •MRAM's

  • spintronics m1-nano

  • spin symmetries

  • babags rrrrrrrr

  • ??? ???

  • atoms

  • screens repulsion between

  • magnetic exchange

  • spatial spin


Sujets

Informations

Publié par
Nombre de lectures 22
Poids de l'ouvrage 1 Mo
ChapterV: spintronicsMagnetismanditinerantmagnetism•Giantmagnetoresistance•Hard disksmagneticheads•Spin valve effect•MRAM’sSpintronicsM1-Nano1
rψχ)(ψψψψψ121221=rrrrrrrrrRrRrRrRXEABABsnoineewtebnoislupersneercs egrahcnortcele SG nI,ψψrrSGXErr)()( niygrene bmoluoC yb tesygrenE»telpirt«1,1,1,1==1,012=+nipsnoitcnufevaWnoitcnufevawcirtemmysitna :elpicnirp iluaPχ0,012==ψψψψψ121221=+rrrrrrrrrRrRrRrRSGABABpalrevosmota :sdiloSAtomsfar away: nooverlapψ(r)⊗χ«singlet»spatialelpicnirp iluaP+noitcaretni bmoluoC :egnahcxecitengaM2onaN-1MscinortnipS
Exchange energy(twoions)antisymmetric(spin tripletF)symmetric(spin singletAF)J (Coulomb) sets spin (magnetic) stateSpintronicsM1-NanoJ αoverlap3
1s7s27SpipExchange energyin atoms(Hund rule)65tnrdo1n0i0=l21x2s24scnf=l1=l3x2np2,32 7Xrra eaetrl=2, 2X54s24p63dntransition metalshM1-Nano41s2
LLLLLLψψψψψψ11()(1)()1(1)()rrrrrrrrAatomiclevelNM1-NanonSpintronicsgMost commonspin symmetriesisPPPPnSNPPnP==)()()(orrefitnaorref)dnab(snoitcnifevawtnereffidhtiw elbissoppalrevotnereffiDecittal a ni egnahcxE5
dnab d3)ecilsygrenerepsetatsforebmun(setatsfoytisneDhtdiwdnabdna etatsfoytisneD3d levelatomiclevelsNon-magneticmetalspin andbandscoincideFermi surface isnotpolarizedMagneticmetal(Fe, Ni, Co…)spin andbandsshiftedby exchangeenergyJ6M1-NanoThelargerthebandwidth, thelowerthedensityofstates3d bandnarrow, 4d and5d bandwide3d transition metalsare magnetic4 and5d are not(Sboalinddlse)velsSpintronics
uCnadNCopper iedsntiyfosatetNickels3d bandfull3d bandpartiallyfilledFermi levelin wide4s bandFermi levelwheren(εF)smalln(εF)IslargeCondition to getferromagnetismn(εF)J>1SpintronicsStonercriterionM1-Nano7
dnabworranSOD egraLεEEnJKxeFΔ+Δ>>00)(Δ==22222εσεENNnNnKFF)()()(,m=KJJEndεεεε)(desaercnisiygrenecitenik TUBΔ=++=xeEJNJNσσσ4112222222)()(NNN=+snortceleforebmuNεFN=εn(ε)dεJεFN=εn(ε)dεJ8polarizationσ=NNNpotentialenergy(exchange) gained22ΔEex=−JN2NJN2N22Shift 2J betweenspin andbandSpin upgainSpin down gainytilibatsnirenotSonaN-1MscinortnipS
ps rofhtapeerfnaemtnereffid,0,=σσεnF)(evoba 0Fεwoleb 1noitcnuf imreF feerfetats lanifdeipuccoetats laitini=σσεεdkffkkkk13'')()()(htapeerf-naemseitirupmifo noitartnecnoc :cecnatsiserotengamtnaiGn(εF)>n(εF)σl<loCM1-NanoSpintronicsl1,l1cn(εF)cn(εF)smalldiffusionlarge diffusion9, ni
aVel-teFtromedlp(MultilayersofCu-Cosandwidchesassume nospin flip(R+R)4RR(R+R)2(R+R)2SpintronicsR~ciotiraM1-Nano)lResistanceratio(R4+RR)01
rehtOSpintronicsequivalentpictureM1-Nano(Landauer)11