Thermodynamics of the t-J Ladder: A Stable Finite Temperature Density Matrix Renormalization Group Calculation

TL;DR

This paper uses an improved finite temperature DMRG method to simulate a doped t-J ladder, revealing how hole pairs and rung singlets dissociate thermally and how doping affects binding energies and spin gaps.

Contribution

The study introduces an enhanced TDMRG algorithm for stable low-temperature simulations of the t-J ladder, providing detailed thermodynamic insights.

Findings

Thermal dissociation of hole pairs observed.

Evolution of hole pair binding energy with doping.

Magnetic susceptibility and entropy characterized at various doping levels.

Abstract

Accurate numerical simulations of a doped t-J model on a two-leg ladder are presented for the particle number, chemical potential, magnetic susceptibility and entropy in the limit of large exchange coupling on the rung using a finite temperature density matrix renormalization group (TDMRG) method. This required an improved algorithm to achieve numerical stability down to low temperatures. The thermal dissociation of hole pairs and of the rung singlets are separately observed and the evolution of the hole pair binding energy and magnon spin gap with hole doping is determined.