Ising分子基磁性材料的相關(guān)有效場(chǎng)理論.pdf

1、東北大學(xué)碩士學(xué)位論文Ising分子基磁性材料的相關(guān)有效場(chǎng)理論姓名：張起申請(qǐng)學(xué)位級(jí)別：碩士專業(yè)：凝聚態(tài)物理指導(dǎo)教師：魏國(guó)柱2001.12.1東北大學(xué)碩士學(xué)位論文ABSTRACTIsingMolecule—BasedMagnetsStudyByEffective—FieldTheoryWithCorrelationsAbstractMolecule—basedmagnetsareabroad，emergingclassofmagneticm

2、aterialsthatexpandthematerialspropertiesassociatedwithmagnetstoincludelowdensity，transparency，electricalinsulation，andlow—temperaturefabrication，aswellascombinemagneticorderingwithotherpropertiessuchasphotoresponsiveness

3、Essentiallyalloftheconllnonmagneticphenomenaassociatedwitheonventionaltransitionmetalandrareearth—basedmagnetsearlbefoundinmoleculebasedmagnetsAlthoughdiscoveredlessthantwodecadesago，magnetswithorderingtemperaturesexceed

4、ingroomtemperature，veryhighandveryloweoercivities，andsubstantialremanentandsaturationmagnetizationshavebeenachievedTheadventofmoleculebasedmagnetsoffersnewprocessingopportunitiesIn1996，CorineMathoniereeta1synthesizedakin

5、doftwo—dimensionalmolecule—basedmagnetswithspinsresidingonlyindorbitalsconnectedviacovalentbondsAFe“Fe(C204)3[A=N(nCnH2n1)4，n=3—51whichhavecriticaltemperaturesbetween35—48Kandcompensationtemperaturesnear30KThestructureso

6、fthemagnetsarehoneycomblatticewithinterlayercouplingsInordertoclarifythefeaturesofit，themagnetscanbededucedtoamixedspin一2andspin一5／2IsingferrimagneticsystemonalayeredhoneycomblatticeSometheoreticalworksrelatedtothemagnet

7、icsystemhavebeendiscussedbyTKaneyoshiandYNakamuraHowevertheworksshouldbefurtheredWithintheframeworkofeffective—fieldtheorywithcorrelations，wehavestudiedthepropertiesofthemolecule—basedmagnetsanditsvariousvariantsthroughl

8、singmodelindetailThemagneticpropertiesofthemixedspin2andspin5／2Isingferrimagneticsystemonahoneycomblatticewithinterlayercouplingswereinvestigatedbyusingeffective—fieldtheorywithcorrelationsinChap2Theequationsforcalculati

9、ngthegroundstate，themagnetization，thecriticalandcompensationpoint，thetricriticalpoint，theenergyandspecificheat，theinitialsusceptibilityweregivenThenumericalresultshavealsobeenanalyzedandrevealedthatthesystemmayhavetricri

10、ticalpointsandcompensationpointsatcertainconditionsThemagneticpropertiesofthemixedspin一1andspin2lsingferrimagneticsystemandmixedspin3／2andspin5／2lsingferrimagneticsystemwithhomogeneousstructureswereinvestigatedbyusingeff