Unidirectional Rashba spin splitting in single layer WSSealloy.

Atomically thin two-dimensional (2D) layered semiconductors such as transition metal dichalcogenides have attracted considerable attention due to their tunable band gap, intriguing spin-valley physics, piezoelectric effects and potential device applications. Here we study the electronic properties of a single layer WSSealloys. The electronic structure of this alloy, explored using angle resolved photoemission spectroscopy, shows a clear valence band structure anisotropy characterized by two paraboloids shifted in one direction of the-space by a constant in-plane vector.

Evidence for highly p-type doping and type II band alignment in large scale monolayer WSe/Se-terminated GaAs heterojunction grown by molecular beam epitaxy.

Two-dimensional materials (2D) arranged in hybrid van der Waals (vdW) heterostructures provide a route toward the assembly of 2D and conventional III-V semiconductors. Here, we report the structural and electronic properties of single layer WSe grown by molecular beam epitaxy on Se-terminated GaAs(111)B. Reflection high-energy electron diffraction images exhibit sharp streaky features indicative of a high-quality WSe layer produced vdW epitaxy.

Fermi surface and effective masses in photoemission response of the (Ba K )FeAs superconductor.

The angle-resolved photoemission spectra of the superconductor (Ba K )FeAs have been investigated accounting coherently for spin-orbit coupling, disorder and electron correlation effects in the valence bands combined with final state, matrix element and surface effects. Our results explain the previously obscured origins of all salient features of the ARPES response of this paradigm pnictide compound and reveal the origin of the Lifshitz transition. Comparison of calculated ARPES spectra with the underlying DMFT band structure shows an important impact of final state effects, which result for three-dimensional states in a deviation of the ARPES spectra from the true spectral function.

Adsorption of Water and Ammonia on Graphene: Evidence for Chemisorption from X-ray Absorption Spectra.

While the bonding of molecular adsorbates to graphene has so far been characterized as physisorption, our study of adsorbed ammonia and water using near-edge X-ray absorption spectroscopy provides unambiguous evidence for a chemical contribution to the adsorption bond. We use the situation, unique to graphene, to characterize the unoccupied valence band states of the partners in the bond on the basis of the complementary adsorbate and substrate X-ray absorption K edges. New adsorbate-induced features on the substrate (carbon) K edge are interpreted as hybrid states in terms of a simple model of chemical interaction.