Pairing and Excitation Spectrum in doped t-J Ladders

TL;DR

This study uses exact diagonalization to analyze the excitation spectrum of doped t-J ladders, revealing hole pairing, quasiparticle behavior, and the evolution of spin excitations with doping levels.

Contribution

It provides detailed insights into the pairing mechanism and excitation spectrum in doped t-J ladders, highlighting the coexistence of hole pairing and quasiparticle properties.

Findings

Hole pairing in the ground state.

Quasiparticles carry charge +|e| and spin 1/2.

Triplet mode evolves into the spin liquid's triplet band.

Abstract

Exact diagonalization studies for a doped t-J ladder (or double chain) show hole pairing in the ground state. The excitation spectrum separates into a limited number of quasiparticles which carry charge $+|e|$ and spin ${1 \over 2}$ and a triplet mode. At half-filling the former vanish but the latter evolves continuously into the triplet band of the spin liquid. At low doping the quasiparticles form a dilute Fermi gas with a strong attraction but simultaneously the Fermi wavevector, as would be measured in photoemission, is large.