Anisotropic magnetic critical behavior of van der Waals room-temperature ferromagnet Fe5GeTe2 identified by magnetocaloric measurements

Due to the room-temperature Curie temperature and large saturation moment, Fe5GeTe2 is considered a highly attractive van der Waals ferromagnet. Studying its magnetic critical behavior can provide valuable information about its magnetic phase transition. Notably, compared with the conventional methods for studying magnetic critical behavior, such as the modified Arrott plot, scaling analysis based on isothermal magnetic entropy change ΔSM(T,H) has advantages in dealing with the complex magnetic system Fe5GeTe2. However, studies on its magnetic critical behavior based on this method remain completely lacking. Here, we investigate the magnetic critical behavior of Fe5GeTe2 based on its ΔSM(T,H). Through scaling analysis of its ΔSM(T,H), two sets of reliable critical exponents β, δ, and γ are obtained, which are 0.320(8), 7.99(1), and 2.24(2) for H//ab and 0.494(2), 4.28(4), and 1.62(3) for H//c. The significant difference between H//ab and H//c indicates strong anisotropy in its magnetic critical behavior. Furthermore, the fact that the obtained critical exponents for both H//ab and H//c cannot be simply described by a single universality class reveals a crossover of magnetic interactions in Fe5GeTe2.