MAGNETIC STATE OF R(1-X)Y(X)CO(2) COMPOUNDS NEAR THE CRITICAL CONCENTRATION

The substitution of R ions in RCo(2) compounds for non-magnetic yttrium leads to the disappearance of the magnetic moment in the itinerant d-electron subsystem at a critical Y concentration. The magnetic state of the Ho1-xYxCo2 and Er1-xYxCo2 compounds near the corresponding critical concentrations x(c) = 0.58 and x(c) = 0.47 has been studied by means of neutron diffraction, electrical resistivity and a.c. susceptibility measurements. It is found that a long-range magnetic order coexists with a short-range order in a narrow concentration range near x(c) (1 at.% for (Ho,Y)Co-2). The change in magnetic order with Y concentration in both systems occurs through a magnetic phase transition of first order. The properties of the (Ho,Y)Co-2 and (Er,Y)Co-2 compounds near x(c) are strongly affected by the applied magnetic field.