Modulation structure of a frustrated spin ladder

TL;DR

This paper investigates a frustrated two-leg spin-1/2 ladder, revealing a self-organized phase separation with unique elementary excitations and discussing flux phases under magnetic fields.

Contribution

It introduces the concept of a modulation phase with Wigner-like lattice formation and characterizes elementary excitations in a frustrated spin ladder.

Findings

Self-organized phase separation in frustrated spin ladder

Formation of Wigner-like lattice of singlet rungs

Identification of three elementary excitations

Abstract

We study a two-leg spin-1/2 ladder with isotropic exchanges and biquadratic interactions in the basic plaquettes. It is shown that for the extremely frustrated case, the system exhibits a self-organized phase separation. In some parameter regions, the singlet rungs form a Wigner-like lattice in the triplet-rung host. There are three types of elementary excitations in this modulation phase, i.e., the spinons in a triplet domain, the broken singlet rungs and the deformation of the Wigner-like lattice. The flux phase induced by an external magnetic field in the rung-dimerized phase is also discussed.