Phase transitions in the Ising antiferromagnet on the frustrated honeycomb lattice

We present a study of the thermal phase transitions between paramagnetic (PM) and antiferromagnetic (AF) phases in the J(1)-J(2) frustrated honeycomb Ising model. In this model, the competition between AF first-neighbour (J(1) > 0) and second-neighbour (J(2) > 0) interactions can lead to different levels of frustration by tuning the ratio J(2)/J(1). By adopting a cluster mean-field approach, we provide a description of the nature of phase transitions and the role of frustration on the thermodynamics of the model for 0 <= J(2)/J(1) < 1/4. Our results indicate that the Ne ' el temperature vanishes at J(2)/J(1) approximate to 1/4 and only second-order phase transitions are present in the PM-AF phase boundary. Moreover, the thermodynamic quantities are affected by the strongly competitive scenario that takes place for J(2)/J(1) approximate to 1/4. In particular, we found a round maximum in the specific heat and a finite entropy plateau within the PM phase, suggesting strong frustration effects. Therefore, our results suggest that a regime of strong frustration can be found near the PM-AF phase transition for J(2)/J(1) approximate to 1/4.

Automated summary

This study investigates the thermal phase transitions between paramagnetic and antiferromagnetic phases in the J(1)-J(2) frustrated honeycomb Ising model. It reveals that strong frustration effects occur near the PM-AF phase transition when J(2)/J(1) is around 1/4, leading to the disappearance of the Neel temperature and only second-order phase transitions.