Low-temperature transport and crystallographic studies of Er(Co 1− xSi x) 2 and Er(Co 1− xGe x) 2

Abstract

The evolution of the magneto-transport and magneto-elastic anomalies in Si and Ge doped ErCo 2 compounds was studied by means of electrical resistivity and X-ray powder diffraction measurements. The substitution of Ge for Co causes a substantial lattice expansion, which may be one of the reasons for the observed dramatic increase of the Curie temperature observed with Ge doping. A less pronounced enhancement of T C was found with Si doping, which leaves the lattice volume nearly intact. The drop of resistivity at T C observed in ErCo 2 becomes gradually reduced with increasing Si or Ge concentration. Also, both the spontaneous magneto-volume effect and the size of rhombohedral distortion below T C decrease with increasing Si and Ge content, which probably reflects a decreasing magnetic moment of Co.