The interplay between magnetism and superconductivity had attracted immencerninterest and effort following the discovery of magnetic superconductors likernheavy fermion, cuprate and recent iron based superconductors (FebSC). The studyrnof their interplay between has also been fascinating area of study due to complexrnmagnetic interactions in the systems. In the latest, FebSCs the competitionrnbetween antiferromagnetic (AFM) spin density wave (SDW) andrnsuperconductivity (SC) has attracted considerable attention in the current researchrnin the field of superconductivity. The magnetic order in most FebSCs is the resultrnof nesting between hole and electron pockets found at the the center and cornersrnof the unfolded Brillouin zones. The interaction between fermions forming thesernpockets is important to study the low temperature physics of FebSCs. The modelrnHamiltonian consisting of these fermions responsible for magnetic andrnsuperconducting pairing interactions is developed to study their interplay. Usingrneither Green function or Bogoligiv transformation method gap equations forrnSDW and s- wave superconductivity order parameters have been established forrnpure systems and for interacting ones. The gap equations have been studied inrndetail as physically accepted choice of parameters. We have establishedrnexperimentally accepted Electronic Phase diagrams for some FebSCs. First wernstudy the interplay between sign reversal s-wave symmetry superconductivityrn(SC+-) and SDW order parameters and found their homogeneous microscopicrncoexistence in under doped region. On the other hand the competition betweenrnsign preserving s-wave superconductivity (SC++) and SDW order parametersrnproduce their homogeneous overlap near quantum critical point which isrnvi ABSTRACTrnconsistent with the phase diagram of electron doped LaFeAsF compounds.rnWhen the magnetic order is commensurate SDW (SDWc) the interplay calculationrnpresents the first order transition from SDW to SC++ which is consistent with thernphase separated doped FebSCs compounds like doped Li Fe As compounds.rnThe first model calculation results can be compared with the experimental reportrnof doped Ba Fe2 As2 iron based families, doped Sm Fe AsO and electronrndoped LaFe As compounds. Even more interestingly, the result of our studyrnshowed first order transition from SDWc to incommensurate SDW (SDWÎ´) whichrnis directly related to the observed magnetic orders near optimal doped region ofrnBa Fe2 As2. The strong suppression of SDW order parameter in the SC phasesrnand the suppression of superconductivity in both under doped and over dopedrnregions are some of the interesting results