Charge density plateaux and insulating phases in the $t-J$ model with ladder geometry

TL;DR

This paper investigates charge density plateaux and insulating phases in ladder-like $t-J$ systems, analyzing their stability and phase transitions through perturbation theory and numerical diagonalizations.

Contribution

It introduces a detailed analysis of charge density plateaux in $t-J$ ladder systems, combining perturbation theory with Lanczos diagonalizations to understand phase stability.

Findings

Charge density plateaux are stable in certain coupling regimes.

Phase transitions are characterized by first order perturbation theory.

Numerical results support the theoretical phase boundaries.

Abstract

We discuss the occurrence and the stability of charge density plateaux in ladder-like $t-J$ systems (at zero magnetization M=0) for the cases of 2- and 3-leg ladders. Starting from isolated rungs at zero leg coupling, we study the behaviour of plateaux-related phase transitions by means of first order perturbation theory and compare our results with Lanczos diagonalizations for $t-J$ ladders ($N=2\times 8$) with increasing leg couplings. Furthermore we discuss the regimes of rung and leg couplings that should be favoured for the appearance of the charge density plateaux.