简介：AsystematicinvestigationofthemagneticandtransportpropertiesofTidopedLa0.67Ca0.33MnO3wasreported.TheTisubstitutionforMnionsresultsinareductioninferromagnetismandconductivity.Themetal-insulatortransitiontemperatureisclosetoCurietemperaturewhichdecreasesfrom274to82Kasxincreasesfrom0to0.17.ThemostimportanteffectofTidopingistointroducespinclustersinthesamplesduetothedistortionoflocallatticeandtheinhomogeneousmagneticstructureinducedprimarilybytherandomdistributionofMnions.Amaximummagnetoresistanceratioaslargeas90%in1Tat122Kwasobtainedforthesamplewithx=0.055,whichisfourtimeslargerthanthatobtainedforLCMOsampleat272K.Thereisaremarkablefield-historydependentMRinthecoolingprocessforthedopedsampleswhilesuchphenomenondisappearsinthewarmingrun.Theresistivityfollowswellthevariablerangehoppingbehaviorinparamagneticstate.Boththesizeeffectandspindependenthoppingofcarriersbetweenthespinclustersshouldbeconsideredinthissystem.