The Jahn–Teller Distortion Effect on the Magnetic Properties of the Square Lattice

Abstract

In this paper, the Jahn–Teller distortion (JTD) effect on the temperature dependence of magnetization of the square lattice is investigated using the effective field theory developed by Kaneyoshi. We find that the Tc of the square lattice (θ = 90°) is lower than those of z-in (θ < 90°) or z-out (θ > 90°) JTD. Thus, it has a minimum Tc for non-JTD and Tc increases as the JTD increases. Tc-θ curve is conical. However, the square lattice undergoes a magnetic phase transition from ferromagnetic to ferromagnetic at T < Tc and from paramagnetic to ferromagnetic state at the temperature between TcSq < T < TcJTD. Therefore, we propose that the JTD has a strong effect on the magnetic properties of the square lattice.