THE EFFECT OF SMALL SUBSTITUTIONS OF Gd ON THE MAGNETIC PROPERTIES OF SYSTEM Y (?Co?_(1-x) ?Al?_x)?_2

Zaur GAMİSHİDZE¹

Compound Y?Co?_2 is a zonal metamagnet. It was found that partial substitution of cobalt for aluminum in Y?Co?_2 leads to a decrease in the matamagnetic transition field H_m and the emergence of weak zonal ferromagnetism in the system Y(?Co?_(1-x) ?Al?_x )_2 at x?0.12. This can significantly modify the character of the effect of rare-earth impurities on the d–subsystem. To exclude the effect of the crystal¬li¬ne field, gadolinium was used as a magnetizing element. Hence the magne¬tic properties of the system Y_(1-t) ?Gd?_t (?Co?_(1-x) ?Al?_x )_2 were studied in this work. We confined ourselves to the aluminum concentration range (0?x?0.105) in the limits of which initial compounds Y(?Co?_(1-x) ?Al?_x )_2 are paramagnets and undergo a metamagnetic transition in the field. It is shown that, with an increase in the concentration of Gd (with constant concentration of Al), the transition from paramagnetism to ferromagne¬tism takes place. When the content of Al increases, the area of ferro¬magnetism expands, and the paramagnetic state area shrinks. The behavior of the compounds under study in the field depends on the ratio between the degrees of magnetization of cobalt M_Co and gadolinium ? M?_Gd subsystems. If M_(Co ) in a weak field is greater than M_Gd , gadolinium impurities shift the metamagnetic transition field towards weak fields, as the molecular field acting on cobalt from the gadolinium subsystem H_m is summed with the external magnetic field H. .

Keywords
Metamagnetizm, Magnetization, Susceptibility, Density of States, Exchange Interaction ,