1202.6417 (Z. -H. Liu et al.)

Three-dimensionality and orbital characters of Fermi surface in
(Tl,Rb)$_y$Fe$_{2-x}$Se$_2$    [PDF]

Z. -H. Liu, P. Richard, N. Xu, G. Xu, Y. Li, X. -C. Fang, L. -L. Jia, G. -F. Chen, D. -M. Wang, J. -H. He, T. Qian, J. -P. Hu, S. -C. Wang

We report a comprehensive angle-resolved photoemission spectroscopy (ARPES) 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 (BZ) center and a 2D like electron Fermi surface pocket near the zone boundary. The photon energy dependence, the polarization analysis and the LDA 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.

View original: http://arxiv.org/abs/1202.6417