First-Principles Calculations of the Electronic Structure of Tetragonal alpha-FeTe and alpha-FeSe Crystals: Evidence for a Bicollinear Antiferromagnetic Order

Abstract:

       By the first-principles electronic structure calculations, we find that the ground state of PbO-type

  tetragonal-FeTe is in a bicollinear antiferromagnetic order, in which the Fe local moments ( 2:5 B) align    ferromagnetically along a diagonal direction and antiferromagnetically along the other diagonal direction on  the Fe square lattice. This novel bicollinear order results from the interplay among the nearest, the   next-nearest, and the next-next-nearest neighbor superexchange interactions, mediated by Te 5pband. In  contrast, the ground state of FeSe is in a collinear antiferromagnetic order, similar to those in LaFeAsO and  BaFe2As2. This finding sheds new light on the origin of magnetic ordering in Fe-based superconductors.

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http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=2823&context=physics_articles

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