Magnetism and related phenomena in RE(Co1-xSix) compounds

Abstract

We report on crystal structure, magnetic, transport and dilatometric studies of the pseudobinary compounds RE(Co1-xSix)2 with RE = Nd, Ho and Er for x ?? 0.15. The lattice volume of the Ho and Erbased compounds is almost composition invariable, whereas in Nd(Co1-xSix)2 for x between 0 and 0.15 it increases by ? 7%. Already small Si substitutions for Co (x ?? 0.075) induce a dramatic increase of Tc both in the Ho and Er compounds without apparent loss of the first order character of the magnetic phase transition, whereas opposite changes of Tc are observed in Nd analogues. These results, together with variations of resistivity and magnetovolume anomalies at Tc and of the Co magnetic moment observed in all three systems is discussed in terms of expected changes of electronic structure and their influence on the hierarchy of exchange interactions and formation of the Co moment in this class of materials. ?? 1997 Elsevier Science S.A.