Dynamic RKKY induced time-reversal symmetry breaking and chiral spin liquids
Phys. Rev. B 112, 045145 – Published 25 July, 2025
DOI: https://doi.org/10.1103/9vn2-44fk
Abstract
We study the Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction, i.e., the spin-spin interaction mediated by the second-order expansion in the Kondo coupling, in various Kondo lattice systems. We argue that the weak Kondo coupling expansion contains certain physics that is lost in the usual static approximation to the spin susceptibility. Most notably, while the former is sensitive to time-reversal symmetry breaking, the latter is blind to it. Using exact diagonalization on small systems, we show that this enables inducing spin chirality by an external magnetic field. We argue that within the second-order expansion in the Kondo coupling this effect stems from the odd-in-frequency part of the RKKY interaction, which is lost in the zero frequency approximation. To study larger systems, we use a large-N approximation to capture the effect of the dynamic RKKY interaction on U(1) spin liquids. On a honeycomb Kondo lattice with Haldane fluxes for electrons, we show that a nontrivial topology is induced on the spinons resulting in chiral edge states. Our results suggest that dynamic RKKY in combination with an external magnetic field or in proximity to topological electronic materials, can be used as a replacement for a tunable Dzyaloshinskii-Moriya interaction even in centrosymmetric materials.
