Magnetic properties of YMn/sub x/Al/sub 12-x/ (x=4, 5, 6)

摘要

Magnetic susceptibility of YMn/sub x/Al/sub 12-x/ (x=4,5,6) with ThMn/sub 12/ structure was measured at temperatures 90 K to 900 K. These compounds show varied magnetic behaviors depending upon the relative abundance of Mn atoms in the 8f, 8j and 8i crystallographic sites. In the high temperature range, the temperature dependence of the susceptibility is of the Curie-Weiss type. The occurrence of a Mn moment in YMn/sub 4/Al/sub 8/ and YMn/sub 6/Al/sub 6/, is strongly correlated with the critical value d/spl ap/2.6 /spl Aring/ of Mn-Mn distance below which the Mn moment collapses, In YMn/sub 6/Al/sub 6/, both the magnetic and the nonmagnetic Mn atoms were observed to coexist. It has been revealed that the magnetic character of Mn moment in the 8f sites of these two compounds changes from an itinerant electron type to a local moment type with increasing temperature. A transition to a spin glass state at ion temperatures for YMn/sub 5/Al/sub 7/ was suggested,.