Quasiparticle metamorphosis in the random t-J model

TL;DR

This paper investigates the stability and metamorphosis of various quasiparticles in a random t-J model, revealing a doping-induced localization transition in the many-body Hilbert space near a critical doping level.

Contribution

It introduces a novel analysis of quasiparticle stability and their transformation in a disordered t-J model using the FEAST eigensolver, highlighting a localization transition at a critical doping.

Findings

Magnons and JW fermions are more stable than spin-1/2 fermions at low doping.

A critical doping point around p_c=1/3 causes quasiparticle stability to interchange.

Near the critical doping, all quasiparticles become ill-defined, indicating a localization transition.

Abstract

Motivated by the pseudogap-Fermi liquid transition in doped Mott insulators, we examine the excitations of a $t$-$J$ model with random and all-to-all hopping and exchange. The stability of quasiparticles such as spin-1/2 fermions, spin-1 magnons, and emergent Jordan-Wigner (JW) spinless fermions is cast as a problem of localization in the many-body Hilbert space, which is studied by the FEAST eigensolver algorithm. At low dopings, magnons and JW fermions are better defined than spin-1/2 fermions, which are unstable. Upon crossing a critical value of doping around $p_c$ = 1/3, their stabilities are interchanged. Near the critical doping, these quasiparticles are all found to be ill-defined. The critical point is thus associated with a localization transition in the many-body Hilbert space