Abstract
Thetwo-orbitaldouble-exchangemodelisemployedforthestudyofthemagneticandorbitalordersin(RMnO3)n/(AMnO3)2n(R:rareearths;A:alkaline-earthmetal)superlattices.TheA-typeantiferromagneticorderisobservedinabroadregionofparameterspaceforthecaseofSrTiO3assubstrate,inagreementwithrecentexperimentsandfirst-principlescalculationsusingthesesuperlattices.Inaddition,aC-typeantiferromagneticstateisalsopredictedtobestabilizedwhenusingsubstrateslikeLaAlO3withsmallerlatticeconstantsthanSrTiO3,againinagreementwithfirst-principlesresults.ThephysicalmechanismforthestabilizationoftheAandCmagnetictransitionsisdrivenbytheorbitalsplittingofthex2−y2and3z2−r2orbitals.ThissplittingisinducedbytheQ3modeofJahn-Tellerdistortionscreatedbythestraininducedbythesubstrates.Inadditiontothespecialexampleof(LaMnO3)n/(SrMnO3)2n,ourphasediagramscanbevaluableforthecasewherethesuperlatticesarepreparedemployingnarrowbandwidthmanganites.Inparticular,severalnonhomogenousmagneticprofilesarepredictedtooccurinnarrow-bandwidthsuperlattices,highlightingtheimportanceofcarryingoutinvestigationsinthismostlyunexploredareaofresearch.
