From itinerant antiferromagnetism towards localized ferromagnetism in UNi(Al, Ga)

UNiAl is an itinerant antiferromagnet with a transition temperature of 18K and a huge low-temperature Sommerfeld coefficient of 167 mJK sub --2 mole U atoms. A systematic study of the pseudoternary series UNiAl sub 1--x Ga sub x by means of magnetic and specific-heat measurements is presented. The data are interpreted as evidence for a transition from antiferromagnetism to ferromagnetism for x > 0.4 with more localized features in the Ga-rich compounds. For x = 0.4 competition of ferromagnetic and antiferromagnetic interactions causes a complicated behaviour characterized by two types of magnetic transitions. Huge magnetocrystalline anisotropy is responsible for the rather anomalous behaviour of the ferromagnetic compositions. 10 ref.--AA