周期摻雜對(duì)一維反鐵磁海森堡自旋鏈性質(zhì)的影響.pdf

1、揚(yáng)州大學(xué)碩士學(xué)位論文周期摻雜對(duì)一維反鐵磁海森堡自旋鏈性質(zhì)的影響姓名：王春花申請(qǐng)學(xué)位級(jí)別：碩士專業(yè)：凝聚態(tài)物理指導(dǎo)教師：劉擁軍20040501蘭塑型盔堂堡主堂堡堡苧英文摘要(Abstract)ThepropertiesofthegroundstateandlowerenergyexcitedstateofthelowerdimensionalAntiferromagneticHeisenberg(AFH)modelhasbeenoneof

2、thecentralareasofthetheoreticalresearchformanydecadesInordertodeterminewhethertheAFHmodelcarlsetuptheAntiferromagneticlongrangeorderthedimensionatityofthesystemasoneofthekeyfactorsisexploredInparticularthediversesituatio

3、nofquasione—dimensional(QOD)systemsduetotheirvariousgeometricstructuresisfurtherinvestigatedThroughperiodicallydopingspins(sidespin)besideeveryspinsiteofthesamesublatticeoftheonedimensional(1D)AFttlinearchain，weconstruct

4、anewclassofQODAFHspinmodelTheeffectiveexchangeintegralfortheinteractionbetweenthenearestneighborspinsonchainisJ，andr／JisfortheinteractionbetweensidespinsandtheirnearestneighborspinonchainWhen打=1，thecalculationbyexactdiag

5、onalizationshowstirolthesidespinsperiodicallydopedintheSanlesublatticeofafinitechainCaneffectivelystrengthenthespinspincorrelationsinthelargedistanceregion，andmakethetendencyofthechangetofiatByusingSpinWavetheoryandGreen

6、Functionmethod，theeffectsofthesidespinsandthedimensionalityofthesystem(withrespecttOthepropertiesofthegroundstateandthelowerlyingexcitations)wereanalyticallyinvestigatedThisnewQODmodel’spropertiesdiffergreatlyfromthe1DAF

7、HlinearspinchainTherearethreebranchesofexcitationspectrmnofthesystem：oneisgaplessandtheothertwoaregappedAtlowertemperatures，thespecificheatofthesystembehaveslikeTThereisnolongrangeorderatfinitetemperature，whichindicatest

8、hattheMerminWagnertheoremCanapplytothismodelAtgroundstate，thereismagneticlongrangeorderwhen”=1，thatis，sidespinscarlsetupmagnetictongrangeorderwhenperiodicallyaddingsidespins；whilethereisnotwhen叩50Obviouslywiththechanging

9、of叩，thereisaquantumphasetransitioninthissystemAccordingtoourcalculation，thecriticalpointisat矸=0，[KeyWords]：PeriodicallyDoping；QuasiOne—Dimensional；AntiferromagneticQuantumSpinHeisenbergChain；SpinWavetheory；MerminWagnerTh