Spanish users explore interplay between electronic states and structure during Au faceting.
Many fundamental properties of metals are linked the so-called electron Fermi wavelength, namely the wavelength of the conducting electrons. For example, the Fermi wavelength defines the size at which a metal becomes a nanosystem that exhibits quantum mechanical properties. Moreover, at the critical Fermi wavelength size, one can observe an exotic interplay between electronic and structural properties of the metal, giving rise to novel physical phenomena, such as the Mott transition, the Peierls distortions, etc. In the last five years, Ortega's group at the SRC has investigated this problem using model metallic superlattices, namely arrays of linear, monatomic steps on noble metal surfaces.
Ortega's project at the SRC has recently developed an original approach. Using cylindrical metallic surfaces they can smoothly vary the period of the step superlattice and hence tune the Fermi wavelength size. This approach takes advantage of the simplicity and robustness of the Scienta SES 200 setup at the Synchrotron Radiation Center (University of Wisconsin), which permits them to scan the small size synchrotron light over the curved surface, thereby mapping electronic states for each step lattice period. Findings from the SRC experiments, recently published in the New Journal of Physics, allowed Ortega's group to find a large region of two coexisting phases, one of them having the Fermi wavelength periodicity. The conclusion is that such phase separation is actually being prompted by the Fermi-wavelength critical size.