Mott State and Quantum Critical Points in Rare-Earth Oxypnictides $R{O}_{1-x}{F}_{x}FeAs$ ($R=La,Sm,Nd,Pr,Ce$)

Abstract

We investigate the magnetic phase diagram of the newly discovered iron-based high temperature oxypnictide superconductors of the type RO${}_{1-x}$F${}_x$FeAs, with rare earths R=La, Sm, Nd, Pr and Ce by means of {\it ab initio} SGGA and SGGA+U density functional computations. We find undoped LaOFeAs to be a Mott insulator when incorporating electronic correlations via SGGA+U for any physically relevant value of $U$. The doped compounds are according to SGGA conductors with a transition from an antiferromagnetic to a non-magnetic state at a hole doping of concentration $x_c$=0.075 for R=Nd, Pr and at electron doping $x_c$=0.25 for Ce and 0.6 for Sm. Superconductivity in these rare-earth oxypnictides thus appears in the vicinity of a magnetic quantum critical point where electronic correlations are expected to play an important role because of the vicinity of a Mott insulating state at zero doping.

5 pages, 6 figures

References in corpus (2)

• Superconductivity on the border of weak itinerant ferromagnetism in UCoGe
• Hidden Magnetism and Quantum Criticality in the Heavy Fermion Superconductor CeRhIn5

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