We have studied the electronic and magnetic structures of the ternary iron arsenides AFe2As2 (A = Ba, Ca, or Sr) using the first-principles density functional theory. The ground states of these compounds are in a collinear antiferromagnetic order, resulting from the interplay between the nearest and the next-nearest neighbor superexchange antiferromagnetic interactions bridged by As 4p orbitals. The correction from the spin-orbit interaction to the band structure is small. The pressure can reduce dramatically the magnetic moment and diminish the collinear antiferromagnetic order. Based on the calculations, we propose that the low energy dynamics of these materials is described effectively by a t−JH−J1−J2-type model.
@article{arxiv.0806.3526,
title = {Electronic structures of ternary iron arsenides AFe$_2$As$_2$ (A=Ba, Ca, or Sr)},
author = {Fengjie Ma and Zhong-Yi Lu and Tao Xiang},
journal= {arXiv preprint arXiv:0806.3526},
year = {2010}
}
Comments
published version with 26 pages, 14 figures. The electronic band structures and magnetic orders and properties of all three "122" AFe2As2 are reported. An effective model of $t-J_H-J_1-J_2$-type is proposed to describe the low energy dynamics of these materials