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

Gianluca Giovannetti; Sanjeev Kumar; Jeroen van den Brink

doi:10.1016/j.physb.2008.06.008

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arXiv · 0804.0866

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

Gianluca Giovannetti·Sanjeev Kumar·Jeroen van den Brink

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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.

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Gianluca Giovannetti, Sanjeev Kumar, Jeroen van den Brink. 2008-10-31. Mott State and Quantum Critical Points in Rare-Earth Oxypnictides $RO_{1-x}F_xFeAs$ ($R=La, Sm, Nd, Pr, Ce$). https://doi.org/10.1016/j.physb.2008.06.008

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