Critical behavior of the van der Waals ferromagnet Fe4.8GeTe2

The van der Waals ferromagnet Fe5-xGeTe2 has drawn significant interest due to its approximately room-temperature Curie temperature (TC) of 270 to 310 K, which can be regulated through iron deficiency. To comprehend the tunable TC associated with the ferromagnetic exchange mechanism, we systematically investigate the critical phenomenon of Fe5-xGeTe2 (Fe4.8GeTe2) crystals around TC. Employing diverse analytical methods for magnetization study, we derived reliable critical exponent values: TC = 285 K, β = 0.364(2), γ = 1.293(1), and δ = 4.62(1). Through a comparative analysis of these critical exponents, the magnetic behavior of Fe4.8GeTe2 is expounded as a three-dimensional (3D) magnetic exchange mechanism, with exchange distance decay modeled as J(r) ≈ r−4.85, closely resembling long-range magnetic coupling in the 3D Heisenberg mode. © 2024 Elsevier B.V.