WestudytheeffectofSbsubstitutionforPrinthehole-dopedsystemPr0.67Ba0.33MnO3 (PBMO)for different dopinglevelsofSb.Thetwoelectricalresistivitytransitionsobservedinthepristinesample PBMOshifttolowtemperaturesonSbdopingwithanoverallincreaseintheelectricalresistivity.The significantlocallatticedistortionandthegrainboundaryeffectscausedbythelargecationsize mismatchbetweenPr3+ and Sb3+ suppressesthedouble-exchange(DE)interactionandenhancesthe super-exchange(SE)interaction.Thecompoundsshowasignificantandincreasingvalueof magnetoresistanceattemperaturesbelowtheCurietemperature,notexpectedfromtheDEmodel. The CurietemperaturedecreaseswithincreaseinSbcontentbutthesaturationmagnetizationislittle affectedbythesubstitution.Thespins,however,staywellalignedinthelow-temperatureregime.Our X-raynear-edgeabsorptionspectra(XANES)andcorelevelphotoemission(XPS)dataclearlyshowthe Sb cationtobein+3stateandruleoutanypossibilityofe-dopinginourcompounds.
Study of Sb substitution for Pr in the Pr0.67Ba0.33MnO3 system
Bondino F;Magnano E;Parmigiani F;
2009
Abstract
WestudytheeffectofSbsubstitutionforPrinthehole-dopedsystemPr0.67Ba0.33MnO3 (PBMO)for different dopinglevelsofSb.Thetwoelectricalresistivitytransitionsobservedinthepristinesample PBMOshifttolowtemperaturesonSbdopingwithanoverallincreaseintheelectricalresistivity.The significantlocallatticedistortionandthegrainboundaryeffectscausedbythelargecationsize mismatchbetweenPr3+ and Sb3+ suppressesthedouble-exchange(DE)interactionandenhancesthe super-exchange(SE)interaction.Thecompoundsshowasignificantandincreasingvalueof magnetoresistanceattemperaturesbelowtheCurietemperature,notexpectedfromtheDEmodel. The CurietemperaturedecreaseswithincreaseinSbcontentbutthesaturationmagnetizationislittle affectedbythesubstitution.Thespins,however,staywellalignedinthelow-temperatureregime.Our X-raynear-edgeabsorptionspectra(XANES)andcorelevelphotoemission(XPS)dataclearlyshowthe Sb cationtobein+3stateandruleoutanypossibilityofe-dopinginourcompounds.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
