Renormalization group analysis of the spin-gap phase in the one-dimensional t-J model

TL;DR

This paper uses renormalization group analysis to investigate the spin-gap phase in the one-dimensional t-J model, revealing a larger spin-gap region and confirming the universality class of the transition.

Contribution

It provides a new analysis of the spin-gap phase in the 1D t-J model, showing an unexpectedly large spin-gap region and identifying the transition's universality class.

Findings

The spin-gap region is larger than previously thought.

The transition belongs to the $k=1$ SU(2) Wess-Zumino-Witten universality class.

The transition point is determined by level crossing of excitations.

Abstract

We study the spin-gap phase in the one-dimensional t-J model, assuming that it is caused by the backward scattering process. Based on the renormalization group analysis and symmetry, we can determine the transition point between the Tomonaga-Luttinger liquid and the spin-gap phases, by the level crossing of the singlet and the triplet excitations. In contrast to the previous works, the obtained spin-gap region is unexpectedly large. We also check that the universality class of the transition belongs to the $k=1$ SU(2) Wess-Zumino-Witten model.