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BiFeO_3多铁性的第一性原理研究.docx

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BiFeO_3多铁性的第一性原理研究 Introduction: BiFeO3isamultiferroicmaterialthathasgarneredimmenseattentioninrecentyearsowingtotheirintriguingmagneticandferroelectricproperties.Thecombinationofbothferroelectricandmagneticpropertiesinasinglematerialpromptsnumerouspossibilitiesinthefieldofelectronicdevicemanufacturing.Inthispaper,wepresentafirst-principlesstudyofBiFeO3'smultiferroicproperties.Inparticular,westudythemechanismunderlyingBiFeO3'smultiferroicbehaviorbyperformingadensityfunctionaltheory(DFT)basedanalysis. Methodology: Weperformdensityfunctionaltheory(DFT)calculationsusingtheViennaAb-initioSimulationPackage(VASP)tostudythemultiferroicpropertiesofBiFeO3.WeemploytheGGA+Umethodfortheexchange-correlationpotentialtoexaminethemagneticproperties,andweusetheBerryphaseapproachtocomputetheferroelectricpolarization.Weoptimizethestructuresatzerotemperatureuntilforcesoneachatombecomelessthan0.01eV/Å.Weuseak-pointmeshof6×6×6intheBrillouinzonefortheGGA+Ucalculationsandak-pointmeshof8×8×8fortheBerryphasecalculations. Results: WefindthatBiFeO3exhibitsantiferromagneticorderatlowtemperature.TheFeatomsinBiFeO3exhibitaG-typeantiferromagneticconfigurationwhereadjacentFeatomsarealignedinoppositedirections.ThecalculatedspontaneouspolarizationofBiFeO3is89.9μC/cm2,whichalignsalongthe(111)direction.TheferroelectricpolarizationisactivatedbyaparticularFedisplacementalongthe(111)direction,whereFemovestowardstheoxygenanion.ThemagnetoelectriceffectisalsoobservedinBiFeO3,whereanelectricfieldcanalterthemagneticorder. Discussion: WehaveinvestigatedthemultiferroicpropertiesofBiFeO3usingafirst-principlesapproach.OurfindingsdemonstratethatBiFeO3isanantiferromagneticandferroelectricmaterial.TheG-typeantiferromagneticorderresultsfromtheFeatoms'arrangement,whereadjacentFeatomsarealignedinoppositedirections.Thecalculatedspontaneouspolarizationalignsalongthe(111)directionandisinducedbytheFedisplacementtowardstheoxygenanion.Interestingly,wereportthatBiFeO3exhibitsmagnetoelectriceffects,whichimpliesthatthemagneticor