Orbital dependent Rashba splitting and electron-phonon coupling of 2D Bi phase on Cu(100) surface

Abstract

A monolayer of bismuth deposited on the Cu(100) surface forms a highly ordered c(2×2) reconstructed phase. The low energy single particle excitations of the c(2×2) Bi/Cu(100) present Bi-induced states with a parabolic dispersion in the energy region close to the Fermi level, as observed by angle-resolved photoemission spectroscopy. The electronic state dispersion, the charge density localization, and the spin-orbit coupling have been investigated combining photoemission spectroscopy and density functional theory, unraveling a two-dimensional Bi phase with charge density well localized at the interface. The Bi-induced states present a Rashba splitting, when the charge density is strongly localized in the Bi plane. Furthermore, the temperature dependence of the spectral density close to the Fermi level has been evaluated. Dispersive electronic states offer a large number of decay channels for transitions coupled to phonons and the strength of the electron-phonon coupling for the Bi/Cu(100) system is shown to be stronger than for Bi surfaces and to depend on the electronic state symmetry and localization.

Unified Framework for Charge-Spin Interconversion in Spin-Orbit Materials

“…d We assume that most of the current conduction occurs in the conductive layer Cu and calculated the total number of modes based on Cu parameters. e p0 estimated from is ∼ 0.296 (10) using α R = 3.2 × 10 −10 eV-m [53] and v F = 1.57 × 10 6 ms −1 for Cu [51]. Note: v F = 1.87 × 10 6 ms −1 for Bi [51].…”

Molecular Chessboard Assemblies Sorted by Site-Specific Interactions of Out-of-Plane d-Orbitals with a Semimetal Template

“…27 Here we demonstrate that bicomponent mixtures of Pcs, which differ exclusively in their central metal ions (Mn, Co, Cu), sort into highly ordered bimolecular chessboard arrays on the p(10×10) reconstruction of bismuth on Cu(100). [28][29][30][31] The sorting effect is based on sitespecific molecule-substrate interactions between the central transition metal ions and the bismuth template. It is enabled by the square symmetry and the pitch of 1.8 nm of the Bi reconstructed substrate which both match the four-fold symmetry of the Pc molecules and the pitch of the Pc chessboard arrays.…”

“…Differential conductance (dI/dV) spectra recorded at the nodes, rims and pores (Figure 1c) exhibit a u-shape, indicating a reduced density of states around the Fermi level compared to native Cu(100), in-line with the semi-metallic character of bulk Bi. [30][31][32] In contrast, bare Cu(100) features a roughly constant dI/dV spectrum due to its about constant density of states around the Fermi level (E F ). 33 Consequent to the comparably lower density of states of the reconstructed Bi ad-layer at and around E F and due to their in-plane delocalization, 31 a rather weak interaction with molecular adsorbates is expected.…”

“…[30][31][32] In contrast, bare Cu(100) features a roughly constant dI/dV spectrum due to its about constant density of states around the Fermi level (E F ). 33 Consequent to the comparably lower density of states of the reconstructed Bi ad-layer at and around E F and due to their in-plane delocalization, 31 a rather weak interaction with molecular adsorbates is expected. 32 This is in some analogy to the charge distribution of graphene or h-BN leading to a lower interaction with planar polycyclic aromatic compounds.…”

“…(c) The characteristic u-shape of the virtually identical dI/dV spectra (set point: −3 V, −400 pA) obtained at these three sites indicates a lower density of states around the Fermi level compared to native Cu(100). 30,31 Deposition of a binary mixture of CuPc and MnPc (scheme in Figure 2a) by sublimation onto the reconstructed Bi samples held at room temperature leads to self-assembled molecular domains with each molecule appearing as a four-leaved clover (Figure 2b, c).…”