We have performed an angle-resolved photoemission spectroscopy study of a new iron-based superconductor Sr4V2O6Fe2As2. While V 3d orbitals are found to be in a Mott insulator state and show an incoherent peak at ~ 1 eV below the Fermi level, the dispersive Fe 3d bands form several hole- and electron-like Fermi surfaces (FSs), some of which are quasi-nested by the (pi, 0) wave vector. This differs from the local density approximation (LDA) calculations, which predict non-nested FSs for this material. However, LDA+U with a large effective Hubbard energy U on V 3d electrons can reproduce the experimental observation reasonably well. The observed fermiology in superconducting Sr4V2O6Fe2As2 strongly supports that (pi, 0) interband scattering between quasi-nested FSs is indispensable to superconductivity in pnictides.
@article{arxiv.1008.4905,
title = {Fermiology of Sr4V2O6Fe2As2: Quasi-Nested Fe vs Mott-Insulating V Orbitals},
author = {T. Qian and N. Xu and Y. -B. Shi and K. Nakayama and P. Richard and T. Kawahara and T. Sato and T. Takahashi and M. Neupane and Y. -M. Xu and X. -P. Wang and G. Xu and X. Dai and Z. Fang and P. Cheng and H. -H. Wen and H. Ding},
journal= {arXiv preprint arXiv:1008.4905},
year = {2011}
}