Tricritical behaviour of the frustrated Ising antiferromagnet on the honeycomb lattice

TL;DR

This study investigates the phase transitions and tricritical behavior of a frustrated Ising antiferromagnet on a honeycomb lattice using effective-field theory, revealing the impact of cluster size on phase transition nature.

Contribution

It introduces a detailed analysis of how cluster size affects the tricritical point in the phase diagram of the frustrated Ising model on a honeycomb lattice.

Findings

Cluster size significantly influences the existence of the tricritical point.

The phase transition nature changes from second to first order at the tricritical point.

Ground-state energy varies with the frustration parameter R.

Abstract

We use the effective-field theory with correlations based on different cluster sizes to investigate phase diagrams of the frustrated Ising antiferromagnet on the honeycomb lattice with isotropic interactions of the strength $J_1 < 0$ between nearest-neighbour pairs and $J_2 < 0$ between next-nearest neighbour pairs of spins. We present results for the ground-state energy as a function of the frustration parameter $R = J_2 /|J_1|$. We find that the cluster-size has a considerable effect on the existence and location of a tricritical point in the phase diagram at which the phase transition changes from the second order to the first one.