The electronic structure and magnetism of KxFe2Se2

Within the virtual crystal approximation and J1–J2–J3 model, the electronic structures and magnetic properties of iron-selenide KxFe2Se2 (0.0⩽x⩽1.0) are studied by first-principles calculations. Its phase diagram can be classified into two different phases: (I) the collinear antiferromagnetic state (0.0⩽x⩽0.5), and (II) the bi-collinear antiferromagnetic state (0.5⩽x⩽1.0). Such magnetic phases can be well explained by the competition among the nearest, next-nearest, and next-next-nearest neighbor couplings J1, J2, and J3. -- Highlights: ► The electronic structures of KxFe2Se2 are studied by the first-principles calculations. ► Its magnetic phase diagrams can be divided into the stripe antiferromagnetic and bi-collinear antiferromagnetic state. ► Its magnetic phase diagrams are explained by the J1–J2–J3 model.