3×2reconstruction of the Sm/Si(111) interface

Abstract

The initial formation of the samarium/silicon interface is studied by combining scanning tunneling microscopy ͑STM͒, low-energy electron diffraction, and ab initio pseudopotential calculations. A Si(111)3ϫ2-Sm reconstruction is formed at a Sm coverage of 1/6 monolayer. High-resolution STM images reveal a strong bias-voltage dependence for the 3ϫ2 reconstruction. In the empty-state STM images, the rows with a ϫ2 periodicity are shown at high bias voltages, and attributed to Sm atoms. At low bias voltage, an additional double row feature with a ϫ1 periodicity appears and dominates the empty-state image as the bias voltage decreases. The paired protrusions with the ϫ1 periodicity in the double rows in the empty-state image are attributed to Si atoms. In the filled-state STM images, double rows of protrusions forming zigzag chains with a 3ϫ1 structure are observed and assigned to Si atoms. We propose a honeycomb chain-channel model for the 3ϫ2 phase, common to alkali metals and alkaline-earth metals on Si͑111͒. Simulated STM images based on this model are in excellent agreement with experiment.

Self-assembled lead atomic nanowires on pre-structured Sm/Si(111) interfaces

“…In a previous paper [20], we have shown that the empty state STM images, for ''high bias voltage'', present a ·2 periodicity centered on the Sm atoms (Fig. 3a).…”

“…The adsorption of Sm atoms deposited at 1/6 ML coverage on a Si(1 1 1) surface is known to induce a (3 · 2) reconstruction. The HCC model has been proposed for the (3 · 2)-Sm/Si(1 1 1) structure [20] and is represented in Fig. 1.…”

“…The surfaces are formed by the both (3 · 2) and (7 · 1) structures which appear as adsorbatechains induced by the adsorption of Sm atoms on Si(1 1 1) [18][19][20]. Their structure models are based on an appropriate combination of honeycomb chain channel (HCC) and Seiwatz Si chains [18,[21][22][23][24][25][26][27][28].…”

Structural and statistical analysis of Yb/Si(111) and Eu/Si(111) reconstructions

“…In particular, it has been revealed that in the lowest coverage regime, such adsorbates (e.g., Ba, Ca, Mg, Sm, Eu, and Yb) stabilize the well-characterized 3 · 1 and/ or 3 · 2 reconstructions, whose similarity has been confirmed by means of electron diffraction, scanning tunneling microscopy (STM), and surfacecore-level shift (SCLS) measurements ( [1][2][3][4][5][6][7][8][9][10][11] and references therein). These reconstructions have been proposed to possess the honeycomb-chainchannel (HCC) structure [1,[3][4][5][9][10][11].…”

Structural investigation of the quasi-one-dimensional reconstructions induced by Eu adsorption on a Si(111) surface

“…From a scientific point of view, these 1D structures have attracted much attention due to the possibility of observing various exotic physical phenomena, such as formations of non-Fermi-liquid-like ground states, Peierls-like phase transitions, or order-disorder transitions. [1][2][3][4][5][6] The 1D and quasi-1D reconstructions formed by the adsorption of rare-earth metals ͑REMs͒ on a Si͑111͒ surface [7][8][9][10][11][12][13][14][15][16] are candidates for such 1D systems.…”