Magnetic Order in Spatially Disordered Systems

Abstract

Magnetic order in metallic and nonmetallic binary alloys is discussed. A recent model, in which the breakdown of long-range magnetic order in metallic alloys is due to the cooperative change of the moment magnitude with concentration, is illustrated with. examples from nickel alloy systems. Percolation at the critical concentration for long-range order plays a part in these alloy systems, as it does for nonmetallic alloys and metallic alloys in which the magnetic moment magnitude is not so environment dependent. Discussion of the magnetic state in the non long-range ordered composition range leads to a description of spin glasses. The results of recent experiments on the low temperature configuration, the AC susceptibility near the freezing temperature, and the dynamics at all temperatures are presented with the implications for the nature of the spin glass transition.