电子自旋隧穿反平行磁结构的尺度效应

292Vol.29,No.220075CHINESEJOURNALOFLOWTEMPERATUREPHYSICSMay20073(:50502001,60576012,10604001),(:2062004),(:2004A10).:2006210212;:2006210227100022,d.:,,d,,.,d,.,,d.:;.:,,,PACC:7340G,7335C1,[15].,,(:),[611].Majumdar[12],.:,.,[1316][17],.[18],,,.,[19,20],,.,[17],,.,.,.,,,,.,,.,.,,,.2,,GaAs/AlGaAs[5].1,Z0.,(x,y),Bz.[6]:B=Bz(x)z,Bz(x)=B[(x+d/2)-(x-d/2)]()(1)Bz(x)=(M0h){z0/[(x+d/2)2+z20]-z0/[(x-d/2)2+z20]}()(2)1(a);(b);(c)12m3(P+A(x))2+eg32m0¶2Bz(x)(x,y)=E(x,y)(3)m3,P,g3g,=0,+1/-1(1),,A(x)=B(d/2-|x|)(4)A(x)=(M0h)[tan-1((x+d/2)/z0)-tan-1((x-d/2)z0)](5),lB=¶/eB0,c=eB0/m3,rrlB,Bz(x)B0Bz(x),A(x)B0lBA(x),E¶cE.(,GaAs,B0=0.1T,lB=81.3nm,¶c=0.17meV,g3=0.44).x,,(x,y)=eik,y(x),ky.(3)d2dx2-(ky+A(x))2+2E-g32Bz(x)(x,y)=0(6)Ueff(x,ky,)=(ky+A(x))2/2+g3Bz(x)/2,x=d/2.[21]T=1-R=1-m11+m12-m21+m22m11+m21-m21+m22(7)Landaur2Buttiker[22]G=G02/2-/2T(EF,2EFsin(),)cos()d(8)T;x,EF,G0=2e2m3vfly/¶2,vF,lFy.33.11,2ky=0.7,d,:d=0.5,,d,.[23].:,,,.,,,,,.2,d,,ky=0.7;B=3.5;,d,d,3,d.,7312:,d,,;.[24,25].,,.,.,,.,,,..,,.3,,,(a)E/E0=7.5,(b)E/E0=10.0,(c)E/E0=12.5,24,d,;,d,,2,.,,,d..:,d.,,.3.2,.5,d.:,d,,d,.,,.,,d,,,d=1.0,,.delta,delta,,.5,,,ky=0.7;M0h=1.0;z0=0.1;,6,,d.:,.,.,,,83129[18].6,,,(a)E/E0=7.5,(b)E/E0=10.0,(c)E/E0=12.5,57,:,d.,8,.:,,d,d1,;,d,d,,;,,,,,.7,,,:,1,,,;,(1)(4)(2)(5),d,d,z0.,,,.84d,:,d:d,,,;,d,d.,:,,=0=1;.,,,.,,,,.,9312:,.,,,,.[1]KuzmaN.N,KhandelwalP,BarrettS.E.,PfeifferL.N.,WestK.W.Science,281(1998),686690;KhandelwalP,KuzmaN.N,BarrettS.E,PfeifferL.N,WestKW.,PhysRev.,81(1998),673.[2]PrinzGA.,Science,282(1998),1660.[3]BalentsL,EggerR.,PhysRevLett.,85(2000),3464.[4]SebaP,ExnerP,PichuginKN,VyhnalA,StredaP.,PhysRevLett.,86(2001),1598.[5]VoskoboynikovA,LeeC,P,TretyakO.,PhysRevB.,63(2001),165306.[6]MatulisA,PeetersF.M,VasilopoulosP.,PhysRevLett.,72(1994),1518.[7]YouJQ,ZhangLide,GhoshPK.,PhysRevB.,52(1995),17243.[8],,,48(1999),1733.[9]MatulisA,PeetersF.M.,PhysRevB.,62(2000),91.[10]NogretA,BendingSJ.,PhysRevLett.,84(2000),2231.[11]McCordMA,AwschalmD.D.,ApplPhysLett.,57(1990),2153.[12]MajumdarA.,PhysRevB.,54(1996),11911.[13]GuoY,GuB.L,ZongZ,Yu.J,andKawazoneY.,PhysRevB.,62(2000),2635.[14]PappGandPeetersF.M.,ApplPhysLett.,78(2001),2184.[15]XuHZ,OkadaY.,ApplPhysLett.,79(2001),3119.[16]XuHZ,ShiZ.,ApplPhysLett.,81(2002),691.[17]YangXiao2Dong,WangRu2Zhi,GuoYong,YangWei,YuDun2Bo,WangBo,andYanHui,PhysRevB.,70(2004),115303.[18]DobrovolskyV.N,ShekaD.I,CheryachukB.V.,Surf.Sci.,397(1998),333.[19]ZhaiFeng,XuH.Q.,andGuoYong.,PhysRevB.,70(2004),085308.[20]PappGetal..JPhys:CondensMatter.,16(2004),8275.[21]WangRZandYanXH.,ChinPhysLett.,17(2000),598.[22]ButtikerM.,PhysRevLett.,57(1986),1761.[23]LiuXue2WenandStampA.P.,PhysRevB.,50(1994),1588.[24].(,,2001),50.[25],,28(2006),17.SCALEEFFECTOFELECTRONSPINTUNNELINGINASYMMETRICMAGNETICSTRUCTURE3YuanRui2yangWangRu2zhiWeiJin2shengWangBoYanHuiLaboratoryofThinFilmMaterials,BeijingUniversityofTechnology,Beijing100022(Received12October,2006;revisedmanuscriptreceived27October,2007)Inthiswork,usingthetransfermatrixmethod,theeffectofmagneticbarrierscaleonelectronspintunnelinginmagneticquantumstructurewasinvestigated.Theresultsindicatedthatfortheperfectlysimpleidealmodelwhentheincidentenergyofelectronisinvariable,thetransmissionobviouslypresentsineorcosineperiodicityasthemagneticbarrierscaledvaries,andtheperiodicityisindependentofspin.Ontheotherhand,incaseoftherealisticmagneticbarriertheperiodicityoftransmissionisunobviousandnearlydisappears.Itwasalsoshownthattheconductanceisverydifferentbetweentheidealandactualmagneticbarriersasthemagneticbarriersscaledchanges.Allthesephenomenaimplythatthecapabilitiesofdevicesaregreatlyinfluencedbytheirsscale,andthetheoreticalresultswhichareachievedfromtheidealmagneticbarriersmaynotexpressthephysicalessentialofelectronspin2dependenttransportintherealisticmagneticquantumstructure.Keywords:scaleeffect,spintransport,tunnelingconductance,magneticquantumstructuresPACC:7340G,7335C041293TheNationalNaturalScienceFoundationofChina(No.50502001,No.60576012,No.10604001),theNaturalScienceFoundationofBeijing(No.2062004),theBeijingTechnologyNewStarsProject(No.2004A10).