Rashba effect in 2D systems is extensively studied nowadays due to spintronics applications. The Letter studies the fundamentals of spin-orbit interaction in 2D systems. Experimental evidence is claimed for the rotation of the spin polarization vector in Tl/Si from an in-plane Rashba polarization at Γ to the surface normal at K(K′) valleys. These results are possible thanks to the single setup that could measure spin-resolved inverse photoemission (IPES) with in- and out-of- plane sensitivity. This Comment clarifies that (i) when considering the full data set in the Letter, the in-plane polarization does not vanish at the valleys, (ii) the Letter does not explain that the out-of-plane data are not real measurements, in the sense that they are derived by considering the fulfillment of a theoretical symmetry or from an unspecified data treatment.
@article{arxiv.2303.12442,
title = {Comment on "Rotating Spin and Giant Splitting: Unoccupied Surface Electronic Structure of Tl/Si(111)"},
author = {Abraham F. Campos and Kang Wang and Antonio Tejeda},
journal= {arXiv preprint arXiv:2303.12442},
year = {2023}
}