Magnetic Doublon Bound States in the Kondo Lattice Model*

We present a novel pairing mechanism for electrons, mediated by magnons. These paired bound states are termed magnetic doublons. Applying numerically exact techniques (exact diagonalization and the density-matrix renormalization group, DMRG) to the Kondo lattice model at strong exchange coupling J for different fillings and magnetic configurations, we demonstrate that magnetic doublon excitations exist as composite objects with extremely weak dispersion at excitation energies of the order of 3J/2 above the ground state. They are highly stable, support a novel "inverse'' colossal magnetoresistance and potentially other effects like metastable superconductivity, or cooling via quantum distillation.

[1] Rausch, Potthoff, Kawakami arXiv:1909.11896