Low-temperature magnetostriction and distortions in the rare-earth Laves phases

The effects of partial substitution of dysprosium in Tb_0.2Dy_0.8Co₂ by terbium and gadolinium on the structure and magnetic properties have been studied. Two compositions, Tb_0.3Dy_0.7Co₂ and Tb_0.2Dy_0.7Gd_0.1Co₂ have been synthesized. Their crystal structure, in contrast to the structure of the original compound, has both tetragonal distortions and rhombohedral distortions at lower temperatures. Anomalies of magnetostriction and magnetocaloric effect near the observed magnetic phase transitions have been studied. The sign-alternating temperature dependences of the longitudinal and transverse magnetostrictions associated with various types of crystal structure distortions of the alloys are revealed. (paper)