Magnetic properties, electrical resistivity and thermal expansion of (Ho,Y)Co₂

The influence of the Ho substitution on the Co moments in (Ho x Y 1-x )Co 2 has been investigated by means of magnetic, resistivity and lattice parameter measurements. A first-order phase transition and a field-induced metamagnetism can be detected for x>or=0.7. At the magnetic transition temperature anomalies of the lattice parameters were measured for x>or=0.3. In connection with the first-order transition a discontinuity in the rho (T) curves appears for x>or=0.7. For 0.3<or=x<or=0.7 these curves are characterised by the occurrence of minima above T c . At high temperatures (T>150K) the rho (T) curves show a tendency to saturation, which is the same for all x values. Considering the substitution of Ho into YCo 2 the existence of a critical RE concentration (x>0.1) for the appearance of a long-range magnetic order is evidenced. The Co moments mu Co are compared with neutron diffraction results. The overall agreement is very good and supports the assumption of induced Co moments. For the whole pseudobinary system, a Fermi energy situated in a steep flank of the density of states function was assumed.