TY - JOUR

T1 - Atomic chain ordering with ultra-long periods

T2 - Pb/Si(5 5 7)

AU - Czubanowski, Marcin

AU - Pfnür, Herbert

AU - Tegenkamp, Christoph

N1 - Funding information: We gratefully acknowledge the fruitful discussions with Tammo Block. The work is financially supported by the Deutsche Forschungsgemeinschaft .

PY - 2009/8/18

Y1 - 2009/8/18

N2 - As shown previously, Pb on vicinal Si(5 5 7) refacets the surface into a (2 2 3) facet orientation at a Pb coverage of 1.31 ML. This facet formation is electronically stabilized by Fermi nesting and leads to one-dimensional conductance. Electronic correlation seems to be responsible also for the periodic arrangement of atomic Pb chains which decorate the step edges at concentrations exceeding 1.31 ML, up to a concentration of 1.5 ML. Instead of random step decoration, periodicities up to six (2 2 3)-terrace widths (28 lattice constants, 93 Å) have been found. These depend inversely on excess Pb concentration and end at a concentration of 1.52 ML when all steps are decorated with a line density equal to the Si density at steps. These one-dimensional periodicities can be explained assuming that split-off states from surface bands are completely filled by two electrons per Pb atom with corresponding gap opening. This behavior is reminiscent of the formation of charge density waves with tunable wavelengths as a function of excess Pb concentration, and indicates strong electron correlation in this strongly anisotropic 2d system. The alternative, simple band filling within a rigid band model is expected to destabilize the (2 2 3) facet structure upon further adsorption of Pb, which has not been observed.

AB - As shown previously, Pb on vicinal Si(5 5 7) refacets the surface into a (2 2 3) facet orientation at a Pb coverage of 1.31 ML. This facet formation is electronically stabilized by Fermi nesting and leads to one-dimensional conductance. Electronic correlation seems to be responsible also for the periodic arrangement of atomic Pb chains which decorate the step edges at concentrations exceeding 1.31 ML, up to a concentration of 1.5 ML. Instead of random step decoration, periodicities up to six (2 2 3)-terrace widths (28 lattice constants, 93 Å) have been found. These depend inversely on excess Pb concentration and end at a concentration of 1.52 ML when all steps are decorated with a line density equal to the Si density at steps. These one-dimensional periodicities can be explained assuming that split-off states from surface bands are completely filled by two electrons per Pb atom with corresponding gap opening. This behavior is reminiscent of the formation of charge density waves with tunable wavelengths as a function of excess Pb concentration, and indicates strong electron correlation in this strongly anisotropic 2d system. The alternative, simple band filling within a rigid band model is expected to destabilize the (2 2 3) facet structure upon further adsorption of Pb, which has not been observed.

KW - Atomic chains

KW - Charge density waves

KW - SPA-LEED

KW - Superlattices

UR - http://www.scopus.com/inward/record.url?scp=70349136672&partnerID=8YFLogxK

U2 - 10.1016/j.susc.2009.08.013

DO - 10.1016/j.susc.2009.08.013

M3 - Article

AN - SCOPUS:70349136672

VL - 603

SP - L121-L124

JO - Surface Science

JF - Surface Science

SN - 0039-6028

IS - 19

ER -