Magnetization process of spin-1/2 Heisenberg antiferromagnets on a layered triangular lattice

TL;DR

This study uses a numerical cluster mean-field method to accurately model the magnetization process of spin-1/2 Heisenberg antiferromagnets on layered triangular lattices, revealing key features like the one-third magnetization plateau and effects of interlayer coupling.

Contribution

The paper introduces a quantitative CMF+S approach to reproduce magnetization curves and analyze interlayer coupling effects in layered triangular lattice antiferromagnets.

Findings

Reproduces the magnetization plateau accurately.

Identifies a small jump and divergence indicating a first-order transition.

Analyzes the impact of weak interlayer coupling on magnetization.

Abstract

We study the magnetization process of the spin-1/2 antiferromagnetic Heisenberg model on a layered triangular lattice by means of a numerical cluster mean-field method with a scaling scheme (CMF+S). It has been known that antiferromagnetic spins on a two-dimensional (2D) triangular lattice with quantum fluctuations exhibit a one-third magnetization plateau in the magnetization curve under magnetic field. We demonstrate that the CMF+S quantitatively reproduces the magnetization curve including the stabilization of the plateau. {We also discuss the effects of a finite interlayer coupling, which is unavoidable in real quasi-2D materials. It has been recently argued for a model of the layered-triangular-lattice compound Ba3CoSb2O9 that such interlayer coupling can induce an additional first-order transition at a strong field. We present the detailed CMF+S results for the magnetization and susceptibility curves of the fundamental Heisenberg Hamiltonian in the presence of magnetic field and weak antiferromagnetic interlayer coupling. The extra first-order transition appears as a quite small jump in the magnetization curve and a divergence in the susceptibility at a strong magnetic field ~ 0.712 of the saturation field.