Electronic and magnetic structures of ternary iron selenides AFe2Se2 (A=K, Cs, or Tl)
Abstract
By the first-principles electronic structure calculations, we find that the ground state of ternary iron selenides AFe2Se2 (A=K, Cs, or Tl) is in a bi-collinear antiferromagnetic order, in which the Fe local moments (2.8μB) align ferromagnetically along a diagonal direction and antiferromagnetically along the other diagonal direction on the Fe-Fe square lattice. This bi-collinear antiferromagnetic order results from the interplay among the nearest, the next nearest, and the next next nearest neighbor superexchange interactions, mediated by Se 4p-orbitals.
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