title: Electronic structures and magnetic order of ordered-Fe-vacancy ternary iron selenides TlFe1.5Se2 and AFe1.5Se2 (A=K, Rb, or Cs).
abstract: By the first-principles electronic structure calculations, we find that the ground state of the Fe-vacancies ordered TlFe(1.5)Se(2) is a quasi-two-dimensional collinear antiferromagnetic semiconductor with an energy gap of 94 meV, in agreement with experimental measurements. This antiferromagnetic order is driven by the Se-bridged antiferromagnetic superexchange interactions between Fe moments. Similarly, we find that crystals AFe(1.5)Se(2) (A=K, Rb, or Cs) are also antiferromagnetic semiconductors but with a zero-gap semiconducting state or semimetallic state nearly degenerated with the ground states. Thus, rich physical properties and phase diagrams are expected.
authors.affiliation: Department of Physics, Renmin University of China, Beijing 100872, China.
authors.forename: Xun-Wang
authors.initials: XW
authors.lastname: Yan
authors.forename: Miao
authors.initials: M
authors.lastname: Gao
authors.forename: Zhong-Yi
authors.initials: ZY
authors.lastname: Lu
authors.forename: Tao
authors.initials: T
authors.lastname: Xiang