Reversible step period rearrangement and carbon segregation have been observed on clean nickel single-crystal surfaces whose bulk is also relatively free of impurities. These transitions occurred over a temperature range of 35 K at the nickel Curie temperature, as determined by simultaneous low-energy electron diffraction, Auger, and permeability measurements on nickel stepped and flat (111) surfaces. The observation of segregated carbon in carbidic form (isolated carbon atoms) indicates an unusual bonding state of C to the surface below the Curie temperature. Measured carbon coverages indicate a change in the heat of segregation of greater than 0.2 eV per carbon atom at the Curie point.
Citation: Physical Review B (Condensed Matter and Materials Physics)
Pub Type: Journals