Collinear N\'eel-type ordering in partially frustrated lattices

TL;DR

This paper investigates how partial frustration in specific antiferromagnetic lattices leads to collinear Ne9el-type ordering in the ground state, using linear spin wave theory to analyze energy and excitations.

Contribution

It introduces a model of partially frustrated lattices with variable bond strength and identifies conditions for Ne9el ordering, providing analytical insights into their ground states.

Findings

Ne9el ordering occurs below a critical bond strength ratio b5_c.

Ground state energy and excitation spectrum are computed using linear spin wave theory.

The model reveals the influence of partial frustration on magnetic ordering.

Abstract

We consider two partially frustrated S = 1/2 antiferromagnetic spin systems on the triangular and pentagonal lattices. In an elementary plaquette of the two lattices, one bond has exchange interaction strength $\alpha$ ($\alpha \leq 1$) whereas all other bonds have exchange interaction strength unity. We show that for $\alpha$ less than a critical value $\alpha_{c}$, collinear N\'eel-type ordering is possible in the ground state. The ground state energy and the excitation spectrum have been determined using linear spin wave theory based on the Holstein-Primakoff transformation.