Magnetic states of iron-based two-leg ladder tellurides

Abstract

The recent discovery of superconductivity at high pressure in the two-leg ladder compounds BaFe${}_2{X}_3$ ($X$=S, Se) started the novel field of quasi-one-dimensional iron-based superconductors. In this publication, we use Density Functional Theory (DFT) to predict that the previously barely explored ladder compound RbFe${}_2$Te${}_3$ should be magnetic with a CX-type arrangement involving ferromagnetic rungs and antiferromagnetic legs, at the realistic density of $n=5.5$ electrons per iron. The magnetic state similarity with BaFe${}_2$S${}_3$ suggests that RbFe${}_2$Te${}_3$ could also become superconducting under pressure. Moreover, at $n=6.0$ our DFT phase diagrams (with and without lattice tetramerization) reveal that the stable magnetic states could be either a 2$\times$2 magnetic Block-type, as for $X$=Se, or a previously never observed before CY-type state, with ferromagnetic legs and antiferromagnetic rungs. In the Te-based studies, electrons are more localized than in S, implying that the degree of electronic correlation is enhanced for the Te case.

9pages, 7 figures