鈣鈦礦型錳氧化物的結(jié)構(gòu)、磁和電輸運(yùn)性質(zhì).pdf

1、天津大學(xué)博士學(xué)位論文鈣鈦礦型錳氧化物的結(jié)構(gòu)、磁和電輸運(yùn)性質(zhì)姓名：劉新軍申請(qǐng)學(xué)位級(jí)別：博士專業(yè)：材料物理與化學(xué)指導(dǎo)教師：姜恩永李志青20070601摘要AbstractThemanganitewithaperovskitestructurehasbeenattracmdalotofattentionincondensedmatterphysicsandmaterialphysicssincethediscoveryofthecolossa

2、lmagnetoresistance(CMR)phenomenon，notonlybecauseofthepotentialapplicationsofCMReffectinmagneticfieldsensors，magneticreadingheadsandmagneticrandomaccessmemories，butalsobecauseofmanyintriguingphysicalpropertiesobservedinth

3、istypeofoxideQn產(chǎn)h禽stheinsulatormetaltransitioninducedbytheappliedmagneticfield，theelecstructuralphaseseparationInthisthesis，wehaveinvestigatedthestructural，magneticandelectricaltransportpropertiesofmanganitesthroughdopin

4、gontheA—andB—siteintheperovskitemanganitesThe●mainresultsaregeneralizedasfollows：WehavepreparedtheferromagneticinsulatingmanganiteNdossNao19Vln03polycrystallinesamplebyPechiniprocessThemagneticresearchesindicatethatthesh

5、ortrangeferromagneticorderandparamagneticstatecoexistaroundtheCurietemperature(死)Theelectronspinresonance(ESR)linesatvarioustemperaturesdemonstratethedynamicprocessofthephaseseparationphenomenonwithdecreasingtemperatureI

6、nthehighertemperaturerange，thetemperaturedependenceofESRparametersandelectricalresistivityalediscussedattheframeoftheadiabaticsmallpolaronhoppingmodel，andtheactivationenergiesrelatedtothecreationofthepolaronsandactivatin

7、gthehoppingofthepolaronswereobtainedAcsusceptibilityme舢ementshavedemonstratedthatpolycrystallineFedopedmanganiteLaMno7Feo303isatypicalclusterglass—likestateinthelowtemperaturerangeCombinedwithallresults，weconcludethatmag

8、neticclusters，contributedfromferromagneticinteractionbetweenMn3andMn3Ⅶe3ions，developastemperatureapproachestheorderingtemperature，andcompetewithantiferromagneticinteractionbetweenFe3ionsincharacterofclusterglass1ikestate

9、inlowertemperatureWehavealsoperformedaseriesofmeasurementstostudythelowtemperaturedynamicsofLaMn07Feo303sampleTheresults，obtainedintheZerOfieldcooledandfieldcooleddemagnetizationandmagneticrelaxationdemonstratestrikingme