Co growth on Pt(997): from monatomic chains to monolayer completion

We have used the Pt(997) surface as a deposition template to grow high-density arrays (5×106 cm−1) of parallel Co nanowires. We demonstrate that we can routinely grow ordered arrays of single monatomic chains of Co with precise coverage monitoring by in situ thermal energy atom scattering (TEAS). Nanowires constituted by one or more atomic chains have been characterized as a function of the substrate temperature and coverage by TEAS and scanning tunneling microscopy (STM). We find that, due to slow edge diffusion at low temperature and interlayer mass transport at high temperature, periodic arrays of uniform smooth chains are obtained only between 250 and 300 K. Co deposition in this temperature range results in a uniform coverage of chains having the same average width that can be used to investigate the magnetic properties of one-dimensional structures. The structure of a single-layer Co film has also been investigated: we show that the Co monolayer develops a non-periodic dislocation network upon deposition at 250 K. There is evidence for moderate Co incorporation into the first Pt layer below room temperature.