磁性与弹性The correlation between mechanical stress and magnetic anisotropy

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1、Rep.Prog.Phys.62(1999)809–858.PrintedintheUKPII:S0034-4885(99)79146-3ThecorrelationbetweenmechanicalstressandmagneticanisotropyinultrathinfilmsDSander†Max-Planck-InstitutfurMikrostrukturphysik,Weinberg2,D-06120Halle,Germany¨Received29December1998AbstractTheimpactofstress-drive

2、nstructuraltransitionsandoffilmstrainonthemagneticpropertiesofnmferromagneticfilmsisdiscussed.Thestress-inducedbendingoffilm–substratecompositesisanalysedtoderiveinformationonfilmstressduetolatticemismatchorduetosurface-stresseffects.Themagneto–elasticcouplinginepitaxialfilmsisdet

3、ermineddirectlyfromthemagnetostrictivebendingofthesubstrate.Thecombinationofstressmeasurementswithmagneticinvestigationsbythemagneto-opticalKerreffect(MOKE)revealsthemodificationofthemagneticanisotropybyfilmstress.Stress–strainrelationsarederivedforvariousepitaxialorientationst

4、ofacilitatetheanalysisofthesubstratecurvature.Biaxialfilmstressandmagneto–elasticcouplingcoefficientsaremeasuredinepitaxialFefilmsinsituonWsingle-crystalsubstrates.Tremendousfilmstressofmorethan10GPaismeasuredinpseudomorphicFelayers,andtheimportantroleoffilmstressasadrivingforcefo

5、rtheformationofmisfitdistortionsandforinducingchangesofthegrowthmodeinmonolayerthinfilmsispresented.Thedirectmeasurementofthemagneto–elasticcouplinginepitaxialfilmsprovesthatthemagnitudeandsignofthemagneto–elasticcouplingdeviatefromtherespectivebulkvalue.Evenasmallfilmstrainoford

6、er0.1%isfoundtoinduceasignificantchangeoftheeffectivemagneto–elasticcouplingcoefficient.Thispeculiarbehaviourisascribedtoasecond-orderstraindependenceofthemagneto–elasticenergydensity,incontrasttothelinearstraindependencethatisvalidforbulksamples.†E-mailaddress:sander@mpi-halle

7、.de0034-4885/99/050809+50$59.50©1999IOPPublishingLtd809810DSanderContentsPage1.Introduction8112.Strainandstressinepitaxialgrowth8122.1.Directionaldependenceofelasticproperties8162.2.Elasticpropertiesofvariousepitaxialorientations8173.Magneto–elasticcoupling8223.1.Surfaceeffec

8、tsandstraindependenceofthemagneto–elasticcouplinginultrathinfilms8253