Dynamical structure factors of $S=1/2$ two-leg spin ladder systems

TL;DR

This paper studies the dynamical properties of $S=1/2$ two-leg spin ladder systems, revealing how coupling strength and cyclic four-spin interactions influence excitation modes and structure factors.

Contribution

It provides new insights into how coupling regimes and four-spin interactions affect the dynamical structure factors in two-leg spin ladders.

Findings

Isolated mode appears in strong coupling regime.

In weak coupling, the lowest excited states form a continuum.

Cyclic four-spin interaction significantly alters structure factor distribution.

Abstract

We investigate dynamical properties of $S=1/2$ two-leg spin ladder systems. In a strong coupling region, an isolated mode appears in the lowest excited states, while in a weak coupling region, an isolated mode is reduced and the lowest excited states become a lower bound of the excitation continuum. We find in the system with equal intrachain and interchain couplings that due to a cyclic four-spin interaction, the distribution of the weights for the dynamical structure factor and characteristics of the lowest excited states are strongly influenced. The dynamical properties of two systems proposed for ${\rm SrCu_2O_3}$ are also discussed.