The pressure dependence of the Curie temperature of rare earth-cobalt compounds

The pressure dependence of the Curie temperature (T c ) was determined up to 40 kbar for the compounds R 2 Co 17 (R=Nd, Gd, Er, Y and Th), RCo 5 (R=Gd, Y and Th), R 2 Co 7 (R=Gd and Y), RCo 3 (Gd, Y and Pr) and RCo 2 (R=Gd and Tb). Single phase compounds with off-stoichiometric composition were included in this investigation. The experimental data are discussed in terms of the collective electron model. With few exceptions the pressure derivative of T c of the various compounds can be represented by a general relation of the form dT c /dP= 5 / 3 kappa T c - 5 / 6 kappa B/T c with B=3.5*10 6 K 2 and T c ranging from 400-1200K. For the compounds Y 2 Co 17 , YCo 5 , YCo 3 , YCo 2 , GdCo 5 , ThCo 5 and Th 2 Co 17 the compressibility kappa was determined.