Fractionalized Fermi liquids with the ghost-Gutzwiller Ansatz

Abstract

Fractionalized Fermi liquids ($\mathrm{FL}^{\!*}$), elusive metallic states characterized by fractionalized quasiparticles alongside conventional ones and defying Luttinger's theorem, are prime candidates for the pseudogap regime of underdoped cuprates. We show that a $\mathrm{FL}^{\!*}$ phase emerges in the single-band $t$-$J$ model through a simple ghost-Gutzwiller Ansatz, optimized at the cost of a mean-field calculation. The resulting temperature-doping phase diagram encompasses a low-doping $\mathrm{FL}^{\!*}$, a $d$-wave superconducting dome, and an overdoped conventional Fermi liquid, thereby reproducing key qualitative features of cuprate phenomenology.