The Study On The Effect Of Mn Substitution In Nafeas Superconductor

Abstract

This Work Present The Study On The Effect Of Mn Substitution In Nafeas Applying Densityfunctional Theory (Dft) As Implemented In Quantum Espresso. The Investigation Of Thiseffect Were Done, By 50% Mn-Substitution On Fe Site Of Nafeas. The Crystal Structure Of Thenafeas And N Af E0.5mn0.5as Were Obtained. Convergence Test Were Done. The Band Struc Ture And The Density Of State (Dos) Are Calculated For Non Magnetic (Nm) And Collinear Magnetic(Antiferomagnetic(Afm) And Feromagnetic (Fm)) Orderings. The Calculated Bandstructure And Dos Adopt Properties Of Other Iron Based Superconductors (Ibsc). Compari Son Was Done Between Nafeas And N Af E0.5mn0.5as. The Calculated Band Structures Indi Cates That There Is A Significant Change Due To Mn-Atom In Afm Ordering, Where The Two Bandsare Completely Different At The First ??-Point And In Between The Second ??-Point And The Firstz-Point. There Is Double Degeneracy Nature Of All Bands Along X-M And R-A Points In Nafeasat Each Orderings, But It Decreases In The Fm-Ordering And Completely Disappear In The Afm Ordering. The Nafeas Dos Result Shows That The Fe States Dominated In The Vicinity Of Thefermi Energy Ef With Only A Small Contribution From The As And Na. But Mn And As Showsdominance In The Fm-N Af E0.5mn0.5as At And Near Fermi-Level. Using The Dos Value Andsome Approximation For Bcs Type, The Critical Temperature Tc Were Calculated And Obtainedto Be Tc = 9.33 K For Nafeas, And It Is Suppressed To 8.4 K For N Af E0.5mn0.5as In Nm Ordering.Mn Substituted System Also Shows Decrement Of Tc In The Fm(From 9.36 K To 9.1 K) And Smallenhancement In The Afm Calculations. Concerning To The Dos In The Afm-Nafeas Has Highdos Value.