Chapter 15 - Alkali-adsorbed germanene nanoribbons

Abstract

Alkali and germanium atoms play essential roles in generating plenty of critical condensed matter system, illustrated in well-known lithium-/sodium-ion batteries. They are able to create active chemical environments, resulting in the highly non-uniform and anisotropic chemical bonds of cathode/electrolyte/anode materials. By applying VASP simulations and phenomenological analyses, the creation of interlayer chemical bonds with the Ge-4pz/Ge-(4s, 4px, 4py) orbitals, which are assisted by the finite quantum confinement, exhibited in the coexistent interlayer π/σ/sp3 bonding, the orbital hybridizations in A-Ge bonds (A: alkali), the spin dependent interactions. Furthermore, the sensitive dependences on alkali-adatom concentrations and configurations, the position-dependent valley sites, the highly asymmetric energy spectra about valence holes and conduction electrons, various energy sub-bands in the first Brillouin zone demonstrate the featured quasiparticle behaviors through the adatom- and edge-enriched spin arrangements. Especially, the linear free carrier density due to the alkali-adatom charge transfer is examined, indicating the wear change as varying adatom corresponding to the independent on adatom kind. Thus, the charge transfer might only depend on concentration. In general, the 1D conduction electrons will lead to an outstanding transport property, which is expected to play essential roles in electronic devices.