Magnetic properties of YMnxAl12-x (x=4, 5, 6)

Magnetic susceptibility of YMn_xAl_12-x (x=4,5,6) with ThMn₁₂ 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 YMn₄Al₈ and YMn₆ Al₆, is strongly correlated with the critical value d≈2.6 Å of Mn-Mn distance below which the Mn moment collapses, In YMn₆Al₆, 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 YMn₅Al₇ was suggested,