Co magnetism and related effects in Ho(Co1-xSix)(2)

Magnetic, transport and dilatometric studies of the Ho(Co1-xSix)(2) compoun ds (for x less than or equal to 0.15) are presented. The Si substitution fo r Co yields a dramatic increase of T-c although the room-temperature lattic e volume does not change. The first-order magnetic phase transition at T-c and metamagnetism at higher temperatures observed in HoCo2 persists for x l ess than or equal to 0.075, however the resistivity, magnetoresistance and thermal expansion anomalies become gradually suppressed with increasing x.