Magnetic structures and phase transitions in the pseudobinary Er1−xYxCo3 system

X-ray and neutron diffraction studies as well as magnetization and electrical resistivity measurements of Er1−xYxCo3 compounds were performed. In the Er-rich compounds, , a temperature-induced metamagnetic transition takes place between weak and strong Co magnetic states. In the intermediate concentration region, , below 40 K a spin reorientation was observed. The magnetic structure below the spin-reorientation transition is non-collinear. The Er moments on the 'cubic' sites (6c) are tilted from the c-axis by an angle of about 55°, while those on the uniaxial 3a positions compose a smaller angle, of about 15°. The spin-reorientation transition is accompanied by a large orthorhombic distortion of the hexagonal PuNi3-type crystal structure, which is accounted for by a large anisotropic magnetostriction of the Er sublattice. The distortion parameter varies linearly with x. Its extrapolated value for ErCo3 is about 2 × 10−3. The concentration dependence of both types of magnetic instabilities is depicted in a magnetic phase diagram of the pseudobinary Er1−xYxCo3 system for the low-temperature region.