3D-Ising-type magnetic interactions stabilized by the extremely large uniaxial magnetocrystalline anisotropy in layered ferromagnetic Cr2Te3

Abstract

We investigate the magnetocrystalline anisotropy, critical behavior, and magnetocaloric effect in ferromagnetic-layered Cr₂Te₃. We have studied the critical behavior around the Curie temperature (T_C) using various techniques, including the modified Arrott plot (MAP), the Kouvel-Fisher method (KF), and critical isothermal analysis (CI). The derived critical exponents β = 0.353(4) and γ = 1.213(5) fall in between the three-dimensional (3D) Ising and 3D Heisenberg type models, suggesting complex magnetic interactions by not falling into any single universality class. On the other hand, the renormalization group theory, employing the experimentally obtained critical exponents, suggests 3D-Ising-type magnetic interactions decaying with distance as J(r) = r^−4.89. We also observe an extremely large uniaxial magnetocrystalline anisotropy energy (MAE) of K_u = 2065 kJ/m³, the highest ever found in any Cr_xTe_y based systems, originating from the noncollinear ferromagnetic ground state as predicted from the first-principles calculations. The self-consistent renormalization theory (SCR) suggests Cr₂Te₃ to be an out-of-plane itinerant ferromagnet. Further, a maximum entropy change of -$\Delta S_M^{\max }\approx$ 2.08 J/kg − K is estimated around T_C for the fields applied parallel to the c-axis.