Phases of the generalized two-leg spin ladder: A view from the SU(4) symmetry

TL;DR

This paper explores the complex phase diagram of a generalized two-leg spin ladder with four-spin interactions, revealing a rich multicritical point with various competing orders and a transition governed by Luttinger universality.

Contribution

It introduces a low-energy field theory approach from an SU(4) critical point to unify different dimerized and chiral phases in the spin ladder.

Findings

Identification of a multicritical point unifying multiple phases

Discovery of a scalar chirality phase breaking time-reversal symmetry

Characterization of the phase transition as belonging to the Luttinger universality class

Abstract

The zero-temperature phases of a generalized two-leg spin ladder with four-spin exchanges are discussed by means of a low-energy field theory approach starting from an SU(4) quantum critical point. The latter fixed point is shown to be a rich multicritical point which unifies different competing dimerized orders and a scalar chirality phase which breaks spontaneously the time-reversal symmetry. The quantum phase transition between these phases is governed by spin-singlet fluctuations and belongs to the Luttinger universality class due to the existence of an exact U(1) self-duality symmetry.