Magnetic properties of a PrCoAl4 single crystal

The magnetic properties of a PrCoAl4 single crystal have been studied. In this compound the Co atoms are non-magnetic and the Pr moments order antiferromagnetically at low temperature. In the temperature dependence of the reciprocal susceptibility measured along the a-axis, we observed three peaks at 37 K, 26 K and 15 K. No indications of a magnetic phase transition were found when measurements were made along the b-axis. The chi(-1)(T) curve measured along the c-axis becomes temperature-independent below about 30 Ii a behaviour reminiscent of enhanced Van Vleck paramagnetism. The field dependence of the magnetisation at 4.2 K is strongly anisotropic, Along the c-axis, the Pr moments become forced ferromagnetic after a spin-flop transition at about 0.7 T, reaching 3 mu(B)/Pr at highest field applied (20 T). The magnetic isotherms remain Linear along the b- and a-axes, and even at 20 T the Pr moments are still far from being forced ferromagnetic. (C) 1999 Elsevier Science S.A. All rights reserved.