人工調控結構的金屬薄膜磁性.pdf

1、955531後旦大學博士學位論文人工調控結構的金屬薄膜磁性院專姓系：物理學系業(yè)：塑鐾查塑堡名：里堡些指導教師：金曉峰教授AbstractThelattice—constantofasolidstatematerialiscertainlyakeyparameterindeterminingitsphysicalandchemicalpropertiesAwellcontrolledmanipulationoflatticeconstan

2、thasalwaysbeenadreamtomodulatethepropertiesofmaterialsAsakeyintrinsieparameterofmattermagnetismisalselatedtolatticeconstantRecentlytheSUCCESSofintroducingmagnetismintoelectronics，eggiantmagnetoresistanceeffecthaswakenthe

3、enthusiasm011magnetismespeciallyinlowdimensionMosteffortsarefocused0nspintronicsandtherelationshipbetweenstructureandmagnetismThisthesisworkcontainsseveralattractedtopicsontherelationbetweenstructureandmagnetism，ierealiz

4、ationinexperimentofmanipulatingcontinuouslythelatticeconstantandchemistrythemagnetismoffee—Feandbee—Niinmetastablestructurephase，andtheunusualpropertiesofdirectlymagneticcoupledtrilayersystem(1)Wehavedevelopedanoveltechn

5、iquethatenablestotulleartificiallythesurfacelatticeconstants(”latticeconstautwedge“)豁wellasthesurfacecompositionsr’tompositionwedge’1ofepitaxialfilmsThisworksuggeststhepossibilityofphysicalandchemicalpropertiesofasurface

6、orthinfilmbyfine—tuaingitselectronicstructure(2)WeappliedthelatticeconstantwedgeandcompositionwedgetechniquetoultrathinFefilmsOnCu(001)，oneofthemostimportantyetstillcontroversialnanomagneticsystemsWefoundthatspindensityw

7、aveisindeedthemagneticgroundstateoffccFe，whichisquiterobustagainstlatticeexpansionandAuconcentrationOUthesurface(3)Themagneticcouplingbetweenc(2x2)MnandaNifilminMl!l／NVCu(100)ismanipulatedbyoxygenabsorption0ntheMnsurface

8、TheMnNimagneticcouplingisferromagneticfor私grownfilmbutCanbeswitchedtoantiferromagneticafterachemisorptionof15LangmuirofoxygenonMnStrikinglytheCurietemperature(Tc)ofMn／Nifilmbeforeandaftertheoxygenabsorptionislowerthantha

9、tofthebareNifilm，whereaStheoppositeresultwouldbegenerallyexpectedMonteCarlosimulationsshowthatthecouplingbetweenMnatomsisantiferromagnetic，ratherthantheobservedparallelalignmentInaddition，suche(2x2)Mnoverlayerreducesthes