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

Abstract

The $(1\ifmmode\times\else\texttimes\fi{}1)$ 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 (LDOS) 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 (spintronic) band structure indicates h-BN to be an insulator. The calculated band structure of the $\ensuremath{\pi}$ and $\ensuremath{\sigma}$ 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 (STM) images which are complemented with STM images. From the distance dependence of the LDOS for Ni(111) and h-BN/Ni(111) the apparent height of heteronuclear atomic steps may be derived. From its spin and energy dependence we propose tunneling experiments with strong magnetic contrast.