Dynamics of the phase-change material GeTe across the structural phase transition

(整期优先)网络出版时间:2019-02-12
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ResultsofinelasticneutronscatteringexperinientsandabinitiomoleculardynamicssimulationsforGeTe一theparentcompoundofphase-changematerialsarereported.TheinelasticneutronspectraofGeTepowdersampleshavebeendeterminedinthetemperaturerangeextendingfrom300to700K.Thephononpeaksundergothermalshiftsresultingfromanharmoniceffectsbeingweakerforacousticthanopticmodes.AsmallconcentrationoffreechargecarriesarisingfromthepresenceofGe-vacancieswasfoundnottoaffectsignificantlytheneutronweightedphonondensitiesofstatesofGeTe.Thespectralpatternchangesqualitativelyacrossthestructuralphasetransition,butthelocalstructureofGeTeremainshardlyaffected,asconfirmedbytheanalysisoftemperaturedependenceofthepairdistributionfunctionobtainedfromabinitiomoleculardynamicsinvestigations.Thepresenttheoreticalstudiessupportinawideextentourexperimentalobservationsandalsothoseprovidedbylocalprobemethods.