Critical properties of the quasi-two-dimensional metallic ferromagnet Fe2.85GeTe2

We have investigated the critical behavior of Fe2.85GeTe2 single crystals near the paramagnetic-ferromagnetic transition by bulk dc magnetization measurements. The critical exponents β, γ and δ, obtained from modified Arrott plot, Kouvel-Fisher method, and critical isothermal magnetization analysis, could fulfill the Widom scaling law. The self-consistency and reliability of these exponents are further verified by the magnetic state equations below and above the Curie temperature at high magnetic field. In addition, the exchange distance deduced from the susceptibility exponent is shown to decay as . Based on the observations, we suggest that the competition between direct magnetic exchange and Coulombic and/or RKKY interactions should be responsible for the intrinsic magnetism in this system.