paper

Self-doping effect and possible antiferromagnetism at titanium-layers in the iron-based superconductor Ba $_{2}$ Ti $_{2}$ Fe $_{2}$ As $_{4}$ O

arXiv:1207.6705

Abstract

The electronic structure of Ba $_{2}$ Ti $_{2}$ Fe $_{2}$ As $_{4}$ O, a newly discovered superconductor, is investigated using first-principles calculations based on local density approximations. Multiple Fermi surface sheets originating from Ti-3 $d$ and Fe-3 $d$ states are present corresponding to the conducting Ti $_{2}$ As $_{2}$ O and Fe $_{2}$ As $_{2}$ layers respectively. Compared with BaFe $_{2}$ As $_{2}$ , sizeable changes in the related Fermi surface sheets indicate significant electron transfer (about 0.12 $e$ ) from Ti to Fe, which suppresses the stripe-like antiferromagnetism at the Fe sites and simultaneously induces superconductivity. Our calculations also suggest that an additional NÃ©el-type antiferromagnetic instability at the Ti sites is relatively robust against the electron transfer, which accounts for the anomaly at 125 K in the superconducting Ba $_{2}$ Ti $_{2}$ Fe $_{2}$ As $_{4}$ O.

4+ pages, 4 figures

Self-doping effect and possible antiferromagnetism at titanium-layers in the iron-based superconductor Ba2​Ti2​Fe2​As4​O

Abstract

Self-doping effect and possible antiferromagnetism at titanium-layers in the iron-based superconductor Ba $_{2}$ Ti $_{2}$ Fe $_{2}$ As $_{4}$ O