%0 Journal Article
%T Three-dimensionality and orbital characters of Fermi surface in (Tl,Rb)$_y$Fe$_{2-x}$Se$_2$
%A Z. -H. Liu
%A P. Richard
%A N. Xu
%A G. Xu
%A Y. Li
%A X. -C. Fang
%A L. -L. Jia
%A G. -F. Chen
%A D. -M. Wang
%A J. -B. He
%A T. Qian
%A J. -P. Hu
%A H. Ding
%A S. -C. Wang
%J Physics
%D 2012
%I arXiv
%R 10.1103/PhysRevLett.109.037003
%X We report a comprehensive angle-resolved photoemission spectroscopy study of the tridimensional electronic bands in the recently discovered Fe selenide superconductor (Tl,Rb)$_y$Fe$_{2-x}$Se$_2$ ($T_c=32$ K). We determined the orbital characters and the $k_z$ dependence of the low energy electronic structure by tuning the polarization and the energy of the incident photons. We observed a small 3D electron Fermi surface pocket near the Brillouin zone center and a 2D like electron Fermi surface pocket near the zone boundary. The photon energy dependence, the polarization analysis and the local-density approximation calculations suggest a significant contribution from the Se 4$p_z$ and Fe 3$d_{xy}$ orbitals to the small electron pocket. We argue that the emergence of Se 4$p_z$ states might be the cause of the different magnetic properties between Fe chalcogenides and Fe pnictides.
%U http://arxiv.org/abs/1202.6417v3