Electronic structure and magnetism of doped $A_{x}Fe_{2-y}Se_{2}$

ORAL

Abstract

We develop a new multiorbital t-J Hamiltonian with realistic tight-binding and Heisenberg parameters to study the electronic and magnetic structure of $A_xFe_{2-y}Se_2$ superconductors for 0$<$y$<$0.4. The ARPES experiments are fitted by a tight-binding lattice model with random vacancy order. We find that the vacancy order greatly affects the electronic band structure. For intermediate doping levels 0 $<$ y $<$ 0.4, the stable electronic structure is a compromise between the solution for y=0 and y=0.4. Based on this model, we study the paramagnetic and antiferromagnetic (AFM) phases of $A_{0.8}Fe_{1.6}Se_2$. In the AFM phase the calculated spin susceptibility for the bare band structure agrees with a block-spin structure. This theoretical result is in good agreement with neutron scattering experiments of the spin structure. Furthermore, we show the results on the evolution of low-energy quasiparticle states with electron filling factor in the vacancy-ordered magnetic state.

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Authors

  • Yuan-Yen Tai

    • Dept. of Physics, Univ. of Houston, Houston, Texas 77054, USA

  • Jian-Xin Zhu

    • Theoretical Division, Los Alamos National Laboratory
    • Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
    • Los Alamos National Laboratory
    • Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545

  • Matthias J. Graf

    • Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
    • Los Alamos National Laboratory

  • Chin-Sen Ting

    • Dept. of Physics, Univ. of Houston, Houston, Texas 77054, USA
    • Texas Center for Superconductivity and Department of Physics, University of Houston