TRANSFORMATION FROM A WEAKLY TO STRONGLY FERROMAGNETIC GROUND-STATE IN THE Y1-TLUT(CO0.88AL0.12)(2) SYSTEM

Magnetic characteristics of the Y1-tLut(Co0.88Al0.12)(2) intermetallic system were studied. The ground state was found to change from a weak ly (in Y-rich compounds) to strongly (in Lu-rich compounds) ferromagne tic within the narrow concentration range in the vicinity of t = 0.4. It is supposed that small changes of the density of d-state characteri stics near the Fermi level are able to change the ground state, thus p roviding the abrupt change in the magnetic behaviour of the compounds by substituting Y for Lu. The anomalous T-c(t) dependence of the TmtLu 1-t(Co0.88Al0.12)(2) system is discussed assuming that the d-subsystem of the R(Co0.88Al0.12)(2) compounds with all heavy rare earths, in wh ich it is magnetized by the f-d exchange interaction, is similar to th at of Y(Co0.88Al0.12)(2).