反铁磁半金属ppt课件.ppt

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1、Antiferromagneticsemiconductors:Anewhalf-metallicsystemHisazumiAkaiMasakoOguraDepartmentofPhysicsOsakaUniversityWhatishalf-metallicity?metalliconlyinonespinchannel,sayup.semi-conductingorinsulatingasfortheotherspinchannel,i.e.,down.normallypossibleforalloys,typically2-4components.EFEmetalinsulatorH

2、alf-metallicantiferromagneticsemiconductorsTypicalhalf-metallicalloyshalf-heuslerNiMnSbfull-heuslerCo2MnAlperovskites(CaLa)MnO3doubleperovskitesSr2FeReO6oxidesCrO2zinc-blendesCrAsdilutedmagneticsemiconductors(GaMn)AsAllferromagneticElectronicstructureinmostcases,bandstructurecalculationsareavailabl

3、e.halfandfullheuslersI.GalanakisandP.H.Dederichs,Phys.Rev.B66,174429(2002),B66,134428(2002).zincblendeM.Shirai,J.Appl.Phys.93,6844(2003).I.GalanakisandP.Mavropoulos,Phys.Rev.B67,104417(2003).doubleperovskitesK.I.Kobayashietal.,Nature395,677(1998),Phys.Rev.B59,11159(1999).W.E.Pickett,Phys.Rev.B57106

4、13(1998).FullheusleralloysI.Galanaskisetal.,Phys.RevB66,174429(2002)MagnetizationoffullheusleralloysSlator-PaulinglikebeheviorI.Galanaskisetal.,Phys.RevB66,174429(2002)n=3t1u+3t2g+2eg+1s+3p=12M=Z-24HalfheusleralloysI.Galanaskisetal.,Phys.RevB66,134428(2002)M=Z-18Zinc-blendesM=Z-8DoubleperovskitesK.

5、I.Kobayashietal.,Phys.Rev.B59,11159(1999).EFFe3dFe3dM4d,5dM4d,5d↑↓Sr2FeMoO6half-metallicferroSr2FeWO6antiferroSr2FeReO6half-metallicferroB-siteorderingNewclassofhalf-metallicsystems:DMSDMS:dilutedmagneticsemiconductors(In,Mn)As(Ga,Mn)As(Zn,Co)O,(Zn,V)O(Ga,Mn)N,(Ga,Cr)N(Cd,Mn)GeP2,(Zn,Mn)GeP2(Ti,Cr)

6、O2(Zn,Cr)Se…….TheoreticalApproachtodilutedmagneticsemiconductorsAssAsAsAsAsAsAsAsAsAsAsAsAsAsAsAsAsAsAsAsInInInInInInInInInInInInMnMnMn¯AsAs(In100-x-y-zMn↑xMn↓yAsz)AsH.Akai,Phys.Rev.Lett.81,3002(1998).Carrierinducedferromagnetismandthedopingeffects0.00.10.20246810(In94-xMn6-yMnyAx)AsAsSnConcentra

7、tionofA(%)CarrierconcentrationE(mRy)DE=-n

8、t

9、Mn2+Mn3+Dobleexchangevs.superexchanImpuritybandsSymmetryoforbitalsMn2+Mn3+DE=-

10、t

11、2/JHMn2+Mn3+MechanismofferromagnetismZinc-blendeCrAsferroE=0Rynon-magneticE=0.073