铁基超导体中间隙铁杂质诱导的隙内束缚态的理论研究

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1、摘要铁基超导体中间隙铁杂质诱导的隙内束缚态的理论研究凝聚态物理专业研究生马建明指导教师张德刚教授摘要二零零八年铁基高温超导体的发现，迅速掀起了高温超导研究热潮。与铜氧化物超导体类似，铁基超导体也具有层状结构，但由于独特的铁砷层结构，它比铜氧化物超导体的能带结构更复杂。掺杂会导致铁基超导体的物理性质产生变化。本文基于两轨道四带紧束缚模型，建立了间隙铁杂质系统的哈密顿量，利用波戈留波夫变换对哈密顿量进行对角化，再用格林函数方法计算了间隙铁杂质系统的局域态密度（LDOS）的表达式，对它进行模拟计算并分析结果

2、。结果表明，间隙铁杂质（IFI）点和最近邻铁点上的局域态密度有很强的隙内共振峰，并且随着参数t和的变化而发生明显的改变。共振峰位置和高度仅取决于间隙铁和最I近邻铁之间的跃迁参数t和配对参数。此类隙内束缚态可以通过扫描隧道显微I镜实验直接观察到。关键词：铁基超导体间隙铁杂质局域态密度隙内束缚态IAbstractTheoreticalStudyonIn-gapBoundStatesInducedbyInterstitialFeImpuritiesinIron-basedSuperconductorsM

3、ajor:CondensedmatterphysicsPostgraduate:MaJianmingSupervisor:Prof.ZhangDegangAbstractThediscoveryofiron-basedhightemperaturesuperconductorsin2008hasmotivatedtheinvestigationofhightemperaturesuperconductivity.Similartocopperoxidesuperconductors,iron-base

4、dsuperconductorsalsohavealayeredstructure.Butduetotheiruniqueiron-arseniclayerstructure,iron-basedsuperconductorshavemorecomplexenergybandstructurethancopperoxidesuperconductors.Dopingcanleadtothevariationsofphysicalpropertiesofiron-basedsuperconductors

5、.Basedonthetwo-orbitfour-bandtightbindingmodel,theHamiltonianoftheinterstitialFeimpuritysystemisestablished.TheHamiltonianisdiagonalizedbyusingtheBogoliubovtransformation.Theexpressionofthelocaldensityofstate(LDOS)isderivedbyemployingtheGreen'sfunctionm

6、ethod.Finally,thenumericalcalculationsontheLDOSandtheresultanalysisarecarriedout.ItisshownthattheLDOSattheinterstitialFeimpurity(IFI)andthenearestneighboring(NN)FeofIFIhasthestrongresonancepeaksinsideenergygap,whichlocationsandheightsdependonthehoppingp

7、arametertandthepairingparameterIbetweentheIFIandtheNNFesites.Thesein-gapboundstatescouldbeobservedbyscanningtunnelingmicroscopyexperiments.Keywords：Iron-basedsuperconductors;InterstitialFeimpurities;Localdensityofstates;In-gapboundstatesIII目次目次摘要......

8、.............................................................................................................................IAbstract...............................................................................................