Ab initio Calculation of the Depth‐Dependent Optical Reflectance From Layer‐by‐Layer Atomic Disorder

Abstract

We present a simple model to study the effects of displacing a single atomic monolayer on the linear optical properties of a material. As an example, we calculate the change in reflectance of a Si(111)(1 × 1):H slab after disordering successively deeper atomic layers. We find that the reflectance varies significantly at photon energies above 2.0 eV, and that the disordered slab produces a larger reflectance than the relaxed slab. The results also show a quantitative difference in the contribution from the odd and even atomic layers to the calculated reflectance. This simplified model is a first approach; also, it can be extended to consider more realistic systems that can be probed by techniques such as coherent acoustic phonon (CAP) spectroscopy, and can also be applied to two‐dimensional materials.

Pure spin current injection of single-layer monochalcogenides

“…Of course it would be interesting to understand the detail PSC physics behind the changing of S and Se atoms in Sn and Ge. For instance one could envision a layer by layer analysis of the two layers that conform the monochalcogenides (figure 1) following the scheme developed in [52][53][54][55], in order to elucidate the role of each atomic species at each layer towards their contribution to h e abcd , ( ) m w (equations ( 17)-( 18)), taking special care of the spin degree of freedom. This is a research topic with its own merits but it is out of the scope of the present article, where its main goal was to demonstrate that single-layer SnS, SnSe, GeS and GeSe are excelent candidates to produce on demand spin-current for spintronics applications.…”