Phases from Lightly-Doped Two-Legged Spin Ladders

TL;DR

This paper analytically investigates lightly-doped two-leg spin ladder systems using a t-J model, revealing phase transitions from gapped to gapless states and estimating the deconfinement temperature of spinons and holons.

Contribution

It introduces a bosonization approach to fully account for phase fluctuations and characterizes phase transitions in doped two-leg spin ladders.

Findings

Spin gap evolves to gapless Luttinger liquid phases at certain doping levels.

Transition temperature for electron deconfinement is estimated.

Phase transition depends on doping rate and interchain coupling ratios.

Abstract

We study two-leg spin ladder systems analytically by using a t-J model which includes the interchain spin exchange and the interchain hopping term. The spin part is mapped to a quantum sine-Gordon model via a bosonization method that fully accounts for the phase fluctuation. The spin gap in the Luther-Emery phase evolves to gapless Luttinger liquid phases in even-ladders at certain doping concentration. This transition occurs as doping rate increases and/or the ratio of the interchain spin exchange and hopping to the intrachain couplings decreases. We also estimate the transition temperature at which the conventional electron phase is deconfined to spinon and holon.