Fermi surface evolution and checker-board block-spin antiferromagnetism in $A_x$Fe${}_{2-y}$Se${}_2$

Yuan-Yen Tai, Jian-Xin Zhu, Matthias J. Graf +1

We develop an effective multiorbital mean-field t-J Hamiltonian with realistic tight-binding and exchange parameters to describe the electronic and magnetic structures of iron-sele…