La-Sr-Mn-O基的Mn位摻雜及其Mn-Zn鐵氧體復合材料的結構和磁電阻效應的研究.pdf

1、南昌大學碩士學位論文LaSrMnO基的Mn位摻雜及其MnZn鐵氧體復合材料的結構和磁電阻效應的研究姓名：李文善申請學位級別：碩士專業(yè)：材料物理與化學指導教師：羅廣圣20081201ABSTRACTABSTRACTInthispaperthedevelopmentofmagnetoresitance，principleandapplianceofmagnetoresitanceeffectweresummarizedandmagnetor

2、esitanceeffectofmanganeseoxideswerestudiedThecrystalandelectronicstructureofmanganeseoxidescompound，aswellastheinteractionbetweendouble—exchangeandsuperexchange，themodelofpolaron，theoryofcrystalfieldandJahn—Tellereffectw

3、ereelucidatedTheinfluencefactorofmagneticmaterialsandtheinteractionbetweendifferentferromagnetswereinvestigatedThesampleseriesofLa2／3SrtrjMnlx03(LSMt20)，La2／3Srl／3MnlyFey03(LSMFO)，La2／3Srv3MnlxvFey03(LSMoFO)andLSMO／xMZF(

4、Mn05Zn05Fe204)werepreparedbysolidphasereactionmethodandthestructureandphaseofsampleswerecarriedoutbyXraydiffractioninstrumentBrukerD8madeinGermanyLatticeparameterswereobtainedfromXraybythesoftwareJade50ThemicrostllJctllr

5、℃ofsampleswereobservedbyscanningelectronmicroscopyH一3000madeinJapanThetemperaturedependenceofmagnetoresistance(MR)weremeasuredbyVSMThemaximalmagnetoresistanceWasobtainedinthepointofTCfromthemagnetoresistancecurveTheresul

6、tsofXraydiffractionpatternsshowsthatlatticeconstantsofthreeseriesofsamplesusedbysolidphsaereactionmethodchangelittleandperovskiteorthorhombicstructurewithsinglephasearekeptasthedopingconcentrationicreasesThecrystalstruct

7、ureofFedopedLSMFOhavenotgrownwellandthecrystalhadevidentaperture，whichisprobablyattributedtolowsinteredtemperatureTheresistivityofsamplesLSM口FOincreasemonotonouslyanditsCurietemperaturediscreaseastemperatureincreases，whi

8、chisduetotheloweringofthedoubleexchangeinteractionbetweenMn3andMn4andthuscausestheincreaseinmangnetoresistanceTheresistivityofLSMO／xMZFincreasesasdopedincrease，whichisduetotheFormativetunnelingthroughLSMO／MZF／LSMOtunneli