1. Minimal Model for Study on Superconductivity
in LaFeAsO1-xFx Based on ab-initio Downfolding
R. Arita (Dept. Phys., Univ. Tokyo)
K. Kuroki (Dept. Appl. Phys+Chem., Univ. Electro-Commun.)‏
S. Onari (Dept. Appl. Phys., Nagoya Univ.)‏
H. Usui (Dept. Appl. Phys+Chem., Univ. Electro-Commun.)
H. Kontani (Dept. Phys., Nagoya Univ.)
Y. Tanaka (Dept. Appl. Phys., Nagoya Univ.)
H. Aoki (Dept. Phys., Univ. Tokyo)

2. LDA band structure & MaxLoc Wannier functions
La 4f
Fe 3d
O 2p
As 4p
Maximally localized Wannier functions
(Marzari-Vanderbilt, 97)

3. BZ unfolding G
(p,0)
(p,p) G X M

4. RPA result Fermi Surface Spin susceptibility
yz, xz
x2-y2
Spin susceptibility
Diagonal element of the gap in the orbital rep.
Extended s-wave also by
Mazin et al
Qi et al
Daghofer et al
Nomura
Wang et al
Chubukov et al
X2-y2 orbital has the largest gap

5. Conclusions Model construction based on ab-initio downfolding
5-band model seems to be “minimal”
Possibility of extended-s SC
dx2-y2 orbital has the largest gap
Referecnce: Kuroki et al, arXiv: to appear in Phys. Rev. Lett.