Programme

P.63 -- Poster, VCTP-49

Date: Friday, 2 August 2024

Time: 08:30 - 10:00

Investigation of phase transitions of the frustrated $J_1-J_2$ Ising model on a square lattice in magnetic fields

Pham Huong Thao (1), Ngo Thi Thuan (2), Nguyen Nhu Le (1), Do Duc Phong (1)

(1) Faculty of Physics, University of Education, Hue University; (2) Faculty of Basic Sciences, University of Medicine and Pharmacy, Hue University

The $J_1-J_2$ frustrated Ising model on a square lattice is investigated using the functional integral method with competing interactions $J_1$ (nearest neighbor, antiferromagnetic) and $J_2$ (next nearest neighbor, antiferromagnetic). We determine the ground state of the model including Néel antiferromagnetic and stripe antiferromagnetic phases, which depend on the value of the frustrated parameter $\alpha=J_2/J_1$. For $\alpha=0.5$, the model becomes frustrated because the ground states are infinitely degenerate and there is a discontinuous transition from the Néel antiferromagnetic phase to the stripe antiferromagnetic phase at $\alpha=0.5$. Besides, we also discuss on the effect of spin fluctuations and of longitudinal and transverse fields on order parameters for two cases, $\alpha>0.5$ and $\alpha<0.5$.

Presenter: Pham Huong Thao