Magnetic anisotropy study of UGe₂in a static high magnetic field

UGe₂ has orthorhombic C_mmm crystalline symmmetry and shows ferromagnetic Heavy-Fermion (HF) Superconductor, which provides superconductivity under pressure in the range from 1.0 GPa to 1.5 GPa. Magnetic field dependence of magnetization shows strong magnetic anisotropy. When a magnetic field is applied parallel to easy axis (a-axis), magnetization presents ferromagnetic behavior. At 4.2 K, which is much lower than the Curie temperature T_c 54 K. Spontaneous magnetization is 1.4 μ_B/U, and the magnetization gradually increase with increasing field. On the contrary, when a field is applied parallel to hard axis (b-axis or c-axis), magnetization increases linearly with increasing magnetic field. As for H//b-axis, magnetization is 0.23 μ _B/U even at 27 T. Magnetocrystalline anisotropy constant is obtained as 230 [T μ_B] 3.4[kJ/kg] at 4.2 K. This value is comparable with rare-earth magnet Nd ₂Fe₁₇, which is typical strongly correlated ferromagnet.