Magnetization plateau in the spin ladder with the four-spin exchange

TL;DR

This study investigates the magnetization process in a spin ladder with four-spin exchange interactions, revealing a plateau at half saturation and a Kosterlitz-Thouless phase transition at a critical coupling ratio.

Contribution

It demonstrates the emergence of a magnetization plateau due to four-spin cyclic exchange and characterizes the phase transition as Kosterlitz-Thouless type.

Findings

Magnetization plateau appears at half saturation for J_4 > 0.05.

The phase transition at J_{4c} is of the Kosterlitz-Thouless type.

Critical ratio J_{4c} is approximately 0.05 with a margin of error.

Abstract

The magnetization process of the $S$=1/2 antiferromagnetic spin ladder with the four-spin cyclic exchange interaction at T=0 is studied by the exact diagonalization of finite clusters and size scaling analyses. It is found that a magnetization plateau appears at half the saturation value if the ratio of the four- and two-spin exchange coupling constants $J_4$ is larger than the critical value $J_{4c}=0.05\pm$0.04. The phase transition with respect to $J_4$ at $J_{4c}$ is revealed to be the Kosterlitz-Thouless-type.