Magnetic Doublon Bound States in the Kondo Lattice Model

TL;DR

This paper introduces magnetic doublons, stable magnon-mediated electron pairs in the Kondo lattice model, revealing their properties and potential effects through exact numerical methods.

Contribution

It uncovers a new pairing mechanism involving magnetic doublons in the Kondo lattice model at strong coupling, with detailed numerical analysis.

Findings

Magnetic doublons are stable, weakly dispersive bound states.

They support an inverse colossal magnetoresistance effect.

Numerical evidence from exact diagonalization and DMRG confirms their existence.

Abstract

We present a novel pairing mechanism for electrons, mediated by magnons. These paired bound states are termed ``magnetic doublons''. Applying numerically exact techniques (full 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 very weak dispersion. They are highly stable, support a novel ``inverse'' colossal magnetoresistance and potentially other effects.