Electronic correlations and universal long-range scaling in kagome metals

We investigate the real-space profile of effective Coulomb interactions in correlated kagome materials. By particularizing to ${\mathrm{KV}}_3{\mathrm{Sb}}_5$, ${\mathrm{Co}}_3{\mathrm{Sn}}_2{\mathrm{S}}_2$, FeSn, and ${\mathrm{Ni}}_3\mathrm{In}$, we analyze representative cases that exhibit a large span of correlation-mediated phenomena, and contrast them to prototypical perovskite transition metal oxides. From our constrained random phase approximation studies we find that the on-site interaction strength in kagome metals not only depends on the screening processes at high energy, but also on the low-energy hybridization profile of the electronic density of states. Our results indicate that rescaled by the on-site interaction amplitude, all kagome metals exhibit a universal long-range Coulomb behavior.

Figure 1

(a) Top view of a kagome net formed by correlated cation atoms (gray) decorated with noncorrelated anion atoms (blue), in the typical arrangement seen in ${\mathrm{KV}}_3{\mathrm{Sb}}_5$, ${\mathrm{Co}}_3{\mathrm{Sn}}_2{\mathrm{S}}_2$, FeSn, and ${\mathrm{Ni}}_3\mathrm{In}$. Each kagome atom in the unit cell is represented with its respective local $(x,y)$ frame. The red arrows refer to first ($d_1$) and second ($d_2$) nearest-neighbor atoms. (b) Schematic distribution of the density of states resolved in correlated ($d$) and noncorrelated ($p$) orbital contributions.

Figure 2

Electronic structure of ${\mathrm{KV}}_3{\mathrm{Sb}}_5$ along some high-symmetry lines. The left panel highlights the contribution to the Kohn-Sham states from the correlated $d$ orbitals of vanadium atoms, while the right panel highlights the contribution from the noncorrelated $p$ states of antimony atoms.

Figure 3

Real-space decay of the Coulomb interaction in the kagome systems for the bare potential (red crosses), $dp-dp$ (blue circles), and $d-dp$ (orange stars) models, as well as in $\mathrm{La}{\mathrm{TiO}}_3$, ${\mathrm{LaVO}}_3$, and ${\mathrm{LaCrO}}_3$ (gray squares for $dp-dp$ and pentagons for $d-dp$ models, respectively). The dotted-dashed lines are fits according to the screening models described in the main text.