Atomic mechanisms of the formation of an ordered surface alloy: an STM investigation of

Interpreting STM images of the MnCu/Cu(100) surface alloy

“…The growth [1][2][3][4] and the structural, electronic, and magnetic properties of this system were investigated by quantitative I/V low-energy electron diffraction 5 ͑LEED͒, photoemission, 6,7 and inverse photoemission 6 ͑BIS͒, soft-x-ray absorption ͑SXA͒ and emission [8][9][10] ͑SXE͒, and magnetic circular dicroism 11 ͑CMXD͒. From this we can conclude that c(2ϫ2)MnCu/Cu(100) is structurally welldefined and stable over a large temperature range, with a large magnetic moment for Mn.…”

Diffusion of vacancies in metal surfaces: theory and experiment

“…Calculations on this problem have been performed in the context of the observations on Mn/Cu(0 0 1) that were mentioned previously [48][49][50]. In these calculations it was indeed found that the formation of step vacancies at kinks and the subsequent diffusion of these vacancies along a step and their release into the terrace is the most likely scenario for the creation of surface vacancies in a terrace.…”

“…The first qualitative observation of vacancy-induced motion of embedded atoms was published in 1997 by Flores et al [20]. Using STM, an unusual, low mobility of embedded Mn atoms in Cu(0 0 1) was observed.…”

“…Recently a few STM studies have been performed that shift the emphasis away from steps and focus instead on the large terraces that make up most of the surface [20][21][22][23][24]. A surface vacancy that is formed at one step and annihilated at another does not just cause a net displacement of an atom from the annihilation site to the birth site of the vacancy.…”

“…For metal surfaces, although vacancy creation at a step by direct tip manipulation of the surface has been demonstrated [32], to our knowledge, no studies have been published where the diffusion of artificially created vacancies in a terrace has successfully been measured. The second approach involves the addition of small amounts of appropriate impurities that serve as tracer atoms in the first layer of the surface [20][21][22][23][24]. The presence and passage of a surface vacancy is indirectly revealed by the motion of these embedded atoms.…”