(Our most exciting discovery last year!)

Gamma brass phases in the Cu-Zn system (existing over a wide range - seen in the gray area in the graph, bottom left) all have a Zn4Cu4 kernel as the fundamental building block. The various compositions occur at the remaining crystallographic sites. Theory rationalizes the observed distribution of Cu and Zn among the four sites (through neutron diffraction experiments), and the cluster gives a chemical-based rationale for the pseudogap in the electronic DOS (lower right). We are exploring other examples - Cu/Al, Pd/Zn, etc.