Magnetic properties of a PrCoAl4 single crystal

The magnetic properties of a PrCoAl4 single crystal have been studied. In t his compound the Co atoms are non-magnetic and the Pr moments order antifer romagnetically at low temperature. In the temperature dependence of the rec iprocal susceptibility measured along the a-axis, we observed three peaks a t 37 K, 26 K and 15 K. No indications of a magnetic phase transition were f ound when measurements were made along the b-axis. The chi(-1)(T) curve mea sured along the c-axis becomes temperature-independent below about 30 Ii a behaviour reminiscent of enhanced Van Vleck paramagnetism. The field depend ence of the magnetisation at 4.2 K is strongly anisotropic, Along the c-axi s, 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 ma gnetic isotherms remain Linear along the b- and a-axes, and even at 20 T th e Pr moments are still far from being forced ferromagnetic. (C) 1999 Elsevi er Science S.A. All rights reserved.