Revealing spinons by proximity effect

The ghost-Gutzwiller variational wave function 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.