Ordered alloy films of Ni and Mn grown on Ni(1 1 1)/W(1 1 0)

Ultrathin films of alloyed Ni and Mn have been grown by depositing Mn on 4 ML Ni/W(1 1 0) and annealing to 550 K. Directional Auger electron spectroscopy (DAES) shows that the films have short-range structural order that is at most slightly distorted from the f.c.c. (1 1 1) structure of the Ni film. Low energy electron diffraction (LEED) shows that the films have long-range order due to chemical ordering of the Ni and Mn. Depending on the Ni:Mn ratio, the LEED and DAES are consistent with structures similar to bulk Ni3Mn, bulk NiMn, and with a subsurface structure similar to the (3×3)R30, 2:1 surface alloy observed for Mn/Cu(1 1 1).