新型鐵基超導(dǎo)體laofeas的第一性原理計(jì)算研究

1、武漢理工大學(xué)碩士學(xué)位論文新型鐵基超導(dǎo)體LaOFeAs的第一性原理計(jì)算研究姓名：張法光申請(qǐng)學(xué)位級(jí)別：碩士專業(yè)：凝聚態(tài)物理指導(dǎo)教師：王嘉賦20090501AbstractSincethediscoveryofsuperconductortheresearchofsuperconductivematerialhaspotentialeconomicvalueandwidelyappliedareasbecauseofitsparticular

2、physicalpropertiesEspeciallythediscoveryofhi曲criticaltemperaturecopperoxidesuperconductorssetoffthestudyofhi曲criticaltemperaturesuperconductorHoweverSOfarthereisnooneacknowledgedtheorytoexplainthemechanismofhighcriticalt

3、emperaturesuperconductorandithasseriouslyhamperedthedevelopmentofsuperconductingtechnology功eilewiron—basedhighcriticaltemperaturesuperconductorinFebruaryof2008hasbroadenedthepeoples’thinkingUptonowitscriticaltemperatureh

4、asbreakthrough50KbydopingthelanthanideorunderpressureInmisPaperweusetheCASTEPtaskwhichisbasedonDensityFunctionTheoryinMaterialStudiocomputationsoftwaretostudythepropertyofgroundstateofmothermaterialLaOFeAsdiscussthebands

5、tructureanddensityofstatesindetailWefindthatLa0FeAsisbadmagneticmetal：thedominantstatesattheFermilevelcomefromFe3datomicstatesandpartialAs4patomicstateselectronicsandholesCO—existenceattheFermilevelTheconductionisstrongl

6、yanisotropic，onlyhappeningontheFe—AslayersWeresearchtheelectronicstructureofLaOi^FeAsindifferentFdopingconcentrationusingVirtualCrystalApproximation；discussthedopingeffectoniron—basedsuperconductorcrystalstructureandsupe

7、rconductivityComputationindicatesthattheFdopingmakethestructuremorestableanddecreasethedensityofstatesatFermilevelwhichiSpropitioustosuperconductivitybecauseofeliminatingthespinpolarizedinstabilityWealsofindthatF—dopinga

8、tOxygensiteexcitationO2patomicstatesasthechargelayerwhichiSsimilartothecopperoxidesuperconductorLaOFeAscontainsmagneticelementFewhichisverydifferentfromearlyideasthatmagneticwilldestroythesuperconductingThemagneticmoment

9、calculatedbyDensityFunctionalTheoryiSlargerthantheexperimentvalueInthisarticleweuseLDAUmethodtodealwithsuchastrongcorrelationsystemwithafoCDStoexaminetheelectronicCoulombinteractionontheimpactofLaoFeAshavebeenmoreinlinew

10、iththeexperimentaldataFromthecomputationresultswegivethecausesofmostofironbasedsuperconductoriselectrondoping，thatiS，theCoulombinteractionofdelectronsinhibitholetypechargecarrierthroughtheFermilevel，SOthattheelectronicen

11、ergybanddispersionenhancedThereforetheactualmaterialsshouldfoCUSontheelectronictypedoping。銣傷enUincreasesto45eVtheFermilevelcostsasmallpinnacleandpseudogap，buteveniftheUthenincreased，therehavenotbeenabletodetecttheinsulat