Critical behavior of quasi-two-dimensional semiconducting ferromagnet Cr2Ge2Te6
AbstractThe critical properties of the single-crystalline semiconducting ferromagnet Cr2Ge2Te6 were investigated by bulk dc magnetization around the paramagnetic to ferromagnetic phase transition. Critical exponents β=0.200±0.003 with a critical temperature Tc=62.65±0.07 K and γ=1.28±0.03 with Tc=62.75±0.06 K are obtained by the Kouvel-Fisher method whereas δ=7.96±0.01 is obtained by a critical isotherm analysis at Tc=62.7 K. These critical exponents obey the Widom scaling relation δ=1+γ/β, indicating self-consistency of the obtained values. With these critical exponents the isotherm M(H) curves below and above the critical temperatures collapse into two independent universal branches, obeying the single scaling equation m=f±(h), where m and h are renormalized magnetization and field, respectively. The determined exponents match well with those calculated from the results of the renormalization group approach for a two-dimensional Ising system coupled with a long-range interaction between spins decaying as J(r)≈r−(d+σ) with σ=1.52.