Magnetic states of iron-based two-leg ladder tellurides

Abstract

The recent discovery of superconductivity at high pressure in the two-leg ladder compounds BaFe2X3 (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 RbFe2Te3 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 BaFe2S3 suggests that RbFe2Te3 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 2×2 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.

Pressure-induced orbital-selective metal from the Mott insulator BaFe2Se3

“…The Fermi level is at zero energy and it is shown with dashed (solid) lines. The band structure is more dispersive from to Z than along other directions, which is consistent with the presence of quasi-one-dimensional ladders along the k z axis, in agreement with extant calculations for RbFe 2 Te 3 and BaFe 2 S 3 [36].…”

Block–spiral magnetism: An exotic type of frustrated order

“…An intermediate promising route is the low-dimensional ladders from the family of 123 compounds where accurate DMRG calculations are possible. Early density functional theory and Hartree-Fock results suggest that the effects of correlations are important (37,76) and that noncollinear magnetic order can develop in the ground state (37). The recent proposal of exploring ladder tellurides with a predicted higher value of U /W provides another avenue to consider (76).…”

“…Early density functional theory and Hartree-Fock results suggest that the effects of correlations are important (37,76) and that noncollinear magnetic order can develop in the ground state (37). The recent proposal of exploring ladder tellurides with a predicted higher value of U /W provides another avenue to consider (76). As a consequence, we encourage crystal growers with expertise in iron-based materials to explore in detail the lowdimensional family of 123 compounds, including doped samples, because our results suggest that exotic physics may come to light.…”

Iron telluride ladder compounds: Predicting the structural and magnetic properties of BaFe2Te3

“…Recently, pressure-induced superconductivity was observed in the two-leg quasi-one-dimensional ladder system BaFe 2 X 3 (X = S, Se) with eletronic density n = 6.0 [9,10], starting a novel field of research for high temperature iron-based superconductors [11][12][13][14][15][16][17][18][19][20][21]. BaFe 2 S 3 displays a stripe-type (CX) AFM order, similar to other 2D iron-based superconductors, below 120 K [9,15].…”

“…Hence, it can be reasonably assumed that the magnetic ground state of n = 6 Te-based iron ladders, not synthesized yet, may also display the Block-type order if it can be prepared. Actually, the n = 5.5 iron Te-based ladder was synthesized in experiments [39] but it was recently predicted to display CX-type magnetic order [21]. Considering that the ionic radius of Rb + (∼ 1.47Å) and Ba 2+ (∼ 1.434Å) are similar, we believe it should be possible to prepare Te-based n = 6 iron ladders with chemical formula BaFe 2 Te 3 .…”