Use of angle-resolved photoemission and density functional theory for surface structural analysis of YSi2

Abstract

The atomic structure of two-dimensional yttrium silicide epitaxially grown on Si(1 1 1) was investigated by means of density functional theory calculations and angle-resolved photoemission experiments. The obtained accuracy of the calculations allowed to discriminate different surface arrangements in a quantitative way via comparing their theoretical band structure to the experimental result. Theoretically we find significant changes in the dispersion of a surface localized band upon varying the thickness of the topmost silicon bilayer. For a thickness of 0.4A of the topmost silicon bilayer a strong asymmetry of the surface localized band with respect to C is found, while a thickness of 0.8 A yields a more symmetric dispersion of the band. By comparison with the experimental photoemission results, which show a rather symmetric band around C, we can conclude that the topmost bilayer has a thickness of 0.8 A.

Rare-earth silicide thin films on the Si(111) surface

“…This also holds for Y (the "rare earth" without f electrons). Thus the band structures calculated for Tb, Dy, and Er disilicides are comparable, and indeed very similar, to the band structures calculated by Koitzsch et al [26] and by Rogero et al [24] for the YSi 2 , and by Stauffer et al [21] for the ErSi 2 monolayer on the Si(111) surface. This suggests that the monolayer band structures of the silicides of at least all the trivalent rare earths are qualitatively very similar.…”

“…However, no first-principles calculations at the atomic scale that can confirm or reject the proposed models have been performed for most structures up to date. In general, our theoretical knowledge of the two-dimensional rare-earth silicides is largely incomplete and limited to the simplest Y and Er silicide structures [21,[24][25][26][27][28][29]. To the best of our knowledge, no theoretical investigations of the silicide structures in the submonolayer range are available in the literature.…”

Unveiling the stacking-dependent electronic properties of the 2D ultrathin rare-earth metalloxenes family LnX2 (Ln = Eu, Gd, Dy; X = Ge, Si)

“…Indeed, these systems demonstrated fingerprints of strong 2D ferromagnetic (FM) ordering in the monolayer (ML) limit, 11 together with high carrier mobility, 12 non-trivial topology 13 and remarkable transport phenomena. 14 The electronic band structures of some LnX 2 films were investigated through angle resolved photoemission spectroscopy (ARPES) [15][16][17][18][19][20] and density functional theory (DFT) studies. 10,20,21 However, a systematic study treating the electronic properties of these films as a function of thickness, Ln and host X element is still missing.…”