Density functional theory investigation of the geometric and spintronic structure ofh-BN/Ni(111) in view of photoemission and STM experiments

Abstract

The (1ϫ1) commensurate layer of hexagonal boron nitride on nickel is investigated by density functional theory calculations. The full-potential linear-augmented-plane-wave method is used to obtain total energies for different structural models, the spin-resolved band structure, and local density of states ͑LDOS͒ above the surface. The calculations confirm the accepted structure model of a corrugated layer with nitrogen placed at on-top sites. From the remaining two possibilities for boron the one with boron on fcc hollow sites is energetically slightly favored, but the energy difference to the structure with boron on the hcp hollow site is smaller than the thermal energy during h-BN synthesis. The spin-resolved electronic ͑spintronic͒ band structure indicates h-BN to be an insulator. The calculated band structure of the and bands agrees well with photoemission data. The polarization-induced charge transfer from h-BN to Ni reduces the magnetic moment in the Ni top layer below the bulk value. The LDOS in front of the surface indicates distinct atomic sites in scanning tunneling microscopy ͑STM͒ images which are complemented with STM images. From the distance dependence of the LDOS for Ni͑111͒ and h-BN/Ni͑111͒ the apparent height of heteronuclear atomic steps may be derived. From its spin and energy dependence we propose tunneling experiments with strong magnetic contrast.

Exchange-split interface state at h-BN/Ni(111)

“…Auwärter et al characterized the atomic configuration of h-BN/Ni(111) with scanning tunnelling microscopy (STM). [13] Their results agree with calculations by Grad et al [16] and Huda and Kleinman: [17] The nitrogen atoms are located directly on top of the nickel atoms of the outermost layer. The positions of the boron atoms correspond to the positions of the 3rd layer nickel atoms.…”

“…[18,19] The results of the band structure below the Fermi energy confirm the calculations but the lowest conduction band was found at an energy of 2.7 eV above E F , in contrast to the theoretical prediction. [16] More recent ARUPS results for the occupied bands are again in agreement with the calculations. [16] The unoccupied part of the band structure between the Fermi energy and the vacuum level was investigated with two-photon photoemission (2PPE) by Muntwiler et al.…”

“…For this interface band, Grad et al predict an energetic position between 1.50 eV -1.76 eV above the Fermi energy at Γ, a free-electron-like E(k ) dispersion and an exchange splitting in the range of 130 meV. [16] Nagashima et al investigated the occupied band structure with angle-resolved ultraviolet-photoelectron spectroscopy (ARUPS) and the unoccupied electronic states above the vacuum level with angle-resolved secondaryelectron-emission spectroscopy (ARSEES). [18,19] The results of the band structure below the Fermi energy confirm the calculations but the lowest conduction band was found at an energy of 2.7 eV above E F , in contrast to the theoretical prediction.…”

“…h-BN/Ni(111) was further employed as a substrate for the investigation of C 60 molecules, because the h-BN layer electronically decouples the molecules from the substrate. [12] In recent years, various experimental [13][14][15] and theoretical studies [16,17] were performed on the interface h-BN/Ni(111) to investigate the atomic arrangement as well as the electronic structure. Auwärter et al characterized the atomic configuration of h-BN/Ni(111) with scanning tunnelling microscopy (STM).…”

Tunable self-assembly of one-dimensional nanostructures with orthogonal directions

“…ARPES data, presented in Fig. 2 show r-and p-bands in the binding energy region from 5 to 12 eV, as measured and calculated previously for other h-BN monolayer structures [13]. The orientation of the h-BN layer with respect to the substrate was obtained by a procedure based on the anisotropy of the band structure, which is described in Ref.…”