Magnetic properties of perovskites La0.7Sr0.3 TixO3: Monte Carlo simulation versus experiments
Abstract
ThisworkpresentsaMonteCarlostudyofthephasetransitionintheperovskitesLa0.7Sr0.3Mn0.7
3þ
Mn0.3-x
4þ TixO3 (x¼0.1,0.2,and0.25).Wetakeintoaccountnearest-neighbor(NN)interactionsbetween
magneticionsMn3þ(S¼2) andMn4þ(S = 3/2) usingaspinmodeldescribingastronganisotropyonthe zaxis.WehavecalculatedtheuniformandstaggeredmagnetizationsaswellastheEdwards–Anderson order
parameterasfunctionsoftemperature,withandwithoutanappliedmagnetic field.Fittingtheexperimental
Curie temperatureat x¼0,weestimatedvaluesofvariousexchangeinteractionsinthesystem.Thedominant
one isthatbetweenMn3þ and Mn4þ which isattheoriginoftheferromagneticordering.Effectsofthevery
small interaction J2 betweenNNMn3þ is analyzed:weshowthatitcancauseanantiferromagneticphase
above Tc whichdisappearsatsmaller J2 or atMn3þ concentrationssmallerthan0.55.Ourresultsshowa
goodagreementwithexperimentsonthemagnetizationsforsubstitutionconcentration x¼0.1,0.2and0.3.
Wealsostudiedtheapplied-field effectonthemagnetizationandour obtainedresultsarecomparedwith
experimentsperformedat x = 10%.