Dynamics in two-leg spin ladder with a four-spin cyclic interaction

TL;DR

This study investigates how four-spin cyclic interactions influence the low-energy excitations and order parameters in a two-leg Heisenberg spin ladder, revealing enhanced correlations and long-range order in specific phases.

Contribution

It provides a detailed analysis of the effects of four-spin cyclic interactions on excitation spectra and order parameters using the density-matrix renormalization group method.

Findings

Cyclic interaction enhances spin-spin correlations at specific momenta.

Long-range order in staggered dimer and scalar-chirality phases confirmed.

Presence of delta-function peaks indicates long-range order at zero energy.

Abstract

We study two-leg Heisenberg ladder with four-spin cyclic interaction using the (dynamical) density-matrix renormalization group method. We demonstrate the dependence of the low-lying excitations in the spin wave, staggered dimer order, and scalar-chirality order structure factors on the four-spin cyclic interaction. We find that the cyclic interaction enhances spin-spin correlations with wave vector around momentum $(q_x,q_y)=(\frac{\pi}{2},0)$. Also, the presence of long-range order in the staggered dimer and scalar-chirality phases is confirmed by a $\delta$-function peak contribution of the structure factors at energy $\omega=0$.