Revealing spinons by proximity effect

TL;DR

This paper demonstrates that spinons, fractionalized excitations in a Mott insulator, can be revealed through proximity effects with metals, leading to observable heavy-fermion bands.

Contribution

It introduces a variational wavefunction approach showing spinons can be detected via proximity effects, linking Mott insulators and heavy-fermion phenomena.

Findings

Paramagnetic Mott insulator hosts spinons not visible in single-particle spectrum.

Proximity to a metal causes spinons to acquire charge and reappear as heavy-fermion bands.

The approach provides a new way to detect and study spinons in correlated materials.

Abstract

The ghost-Gutzwiller variational wavefunction within the Gutzwiller approximation is shown to stabilize a genuine paramagnetic Mott insulator in the half-filled single-band Hubbard model. This phase hosts quasiparticles that are crucial to the paramagnetic response without showing up in the single-particle spectrum, and, as such, they can be legitimately regarded as an example of Anderson's spinons. We demonstrate that these spinons at the interface with a metal reacquire charge by proximity effect and thus reemerge in the spectrum as a heavy-fermion band.