Low-energy excitations in a one-dimensional orthogonal dimer model with the Dzyaloshinski-Moriya interaction

TL;DR

This study investigates how the Dzyaloshinski-Moriya interaction influences low-energy excitations in a one-dimensional orthogonal-dimer model, revealing spectral splitting and curvature effects through perturbation and numerical methods.

Contribution

It provides new insights into the impact of DM interaction on triplet excitation spectra in a 1D orthogonal-dimer system.

Findings

DM interaction causes splitting of triplet spectra into separate M=0 and M=±1 branches.

Curvature appears more strongly in M=±1 triplet excitations when DM interaction is present.

Without DM interaction, triplet excitations are flat with three-fold degeneracy.

Abstract

Effects of the Dzyaloshinski-Moriya (DM) interaction on low-energy excitations in a one-dimensional orthogonal-dimer model are studied by using the perturbation expansions and the numerical diagonalization method. In the absence of the DM interaction, the triplet excitations show two flat spectra with three-fold degeneracy, which are labeled by magnetization $M=0,\pm{1}$. These spectra split into two branches with M=0 and with $M=\pm{1}$ by switching-on of the DM interaction and besides the curvature appears in the triplet excitations with $M=\pm 1$ more strongly than those of M=0.