Ferromagnetism of UFe2 and Comparison with the Ferromagnetic Theories

The intermetallic compound UFe₂ is ferromagnetic. A considerable number of magnetization isotherms have been obtained from 200°K down to 4.2°K with applied field up to 14 000 Oe. The Curie temperature has been determined to be 172°K and the Bohr magneton number 1.02 per UFe₂ molecule. Several hysteresis loops at different temperatures have been obtained. The coercive force, the remanence and the loop area are all very small. These data have been compared with existing theories of ferromagnetism. The σ_0T/σ₀₀−T/T_c curve deviates considerably from the molecular field for curve J = ½. The experimental data fit the T^{$\frac{3}{2}$} law better than the T² law. Dyson's formula is valid below T/T_c=0.52 while Bloch's formula is valid below T/T_c=0.35.