Altermagnetism in Heavy Fermion Systems: Dynamic RKKY Interaction Study in Weak Kondo Regime

Chirality in spin systems often arises from the Dzyaloshinskii–Moriya (DM) interaction, which is typically constrained to non-centrosymmetric systems. In heavy fermions or doped Mott insulators, the Higgs effect can impart charge to spinons, enabling control of their chirality. However, these mechanisms are generally ineffective within the Mott regime or under weak coupling between spinons and conduction electrons.

Motivated by our findings from exact diagonalization studies on small systems, we explore the possibility of inducing altermagnetic order in the spin sector through a weak Kondo coupling with conduction electrons, assisted by an external magnetic field. This mechanism aims to generate a tunable dynamic Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction that mediates spin-dependent symmetry breaking characteristic of altermagnets. The weak Kondo coupling gives rise to a dynamic, long-range, and retarded RKKY interaction between localized spins, which we analyze using the Sachdev–Ye formalism in the large-N limit.

Starting from spins on a honeycomb lattice, we demonstrate that breaking time-reversal symmetry in the electron sector can induce alternating spin polarization in momentum space—an essential signature of altermagnetism. To further understand this, we investigate the orbital effects of an external magnetic field on the spin sector and how they modify the symmetry of the induced spin texture.

Finally, while gapless spin liquids are prone to dimerization that breaks translational symmetry, the dynamic RKKY interaction can renormalize spinon hopping amplitudes and potentially restore translational invariance. We analyze the extent to which the RKKY interaction contributes to stabilizing altermagnetic order in correlated spin systems.