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

The insulator/ferromagnet interface system of hexagonal boron nitride on Ni(111) was investigated with spin- and angle-resolved inverse photoemission and spin-polarized secondary electron emission. We identified the theoretically predicted boron nitride (BN) interface state at 1.7 eV above the Fermi level. The interface state is found to be influenced by the ferromagnetic substrate, which is reflected in a magnetic exchange splitting of 130 +/- 50 meV. Parallel to the surface, it shows a free-electron-like E(k(parallel to)) dispersion with an effective mass of 1.1 +/- 0.2m(e). Furthermore, we found a spectral feature at 2.2 eV above the Fermi level, which we attribute to indirect transitions into a region of high density of BN-induced states.