Abstract
Themagneticphasediagramsofmodelsforquasi-one-dimensionalcompoundsbelongingtotheiron-based-superconductorfamilyarepresented.Thefive-orbitalHubbardmodelandthereal-spaceHartree–Fockapproximationareemployed,supplementedbydensityfunctionaltheorytoobtainthehoppingamplitudes.PhasediagramsareconstructedbyvaryingtheHubbardUandHundJcouplingsatzerotemperature.Thestudyiscarriedoutatelectronicdensity(electronsperiron)n=5.0,whichisofrelevanceforthealready-knownmaterialTlFeSe2,andalsoatn=6.0,whererepresentativecompoundsstillneedtobesynthesized.Atn=5.0thereisacleardominanceofstaggeredspinorderalongthechaindirection.Atn=6.0andwiththerealisticHundcouplingJ/U=0.25,thephasediagramisfarricher,includingavarietyof“block”statesinvolvingferromagneticclustersthatareantiferromagneticallycoupled,inqualitativeagreementwithrecentdensitymatrixrenormalizationgroupcalculationsforthethree-orbitalHubbardmodelinadifferentcontext.Theseblockstatesarisefromthecompetitionbetweenferromagneticorder(inducedbydoubleexchangeandprevailingatlargeJ/U)andantiferromagneticorder(dominatingatsmallJ/U).Thedensityofstatesandorbitalcompositionsofthemanyphasesarealsoprovided.
