Surface alloy formation of Fe on Cr(100) studied by scanning tunneling microscopy

Surface alloy formation of Fe on a Cr(100) surface was studied using a UHV scanning tunneling microscope. As we deposited Fe of less than 1 ML at room temperature and subsequently annealed the substrate at temperatures betwee n 200 degrees C and 300 degrees C, we observed that Fe atoms incorporate in to the Cr(100) surface, forming a well-ordered surface alloy of Fe0.5Cr0.5. These two elements were differentiated by imaging at the bias voltages nea r their surface states. The surface alloying was also confirmed by imaging at the bias voltages of their Shockley image states. By annealing the Fe la yer of similar to 1 ML at 250 degrees C, we found that the solubility of Fe into the Cr(100) surface is similar to 25% at that temperature. Fe overlay er shows kinetically roughened mound structure at room temperature while it shows equilibrium two-dimensional islands at 300 degrees C. [S0163-1829(99 )06115-9].