  We undertook an ab-initio study of hexagonal boron nitride (hBN) sandwiched
between Ni(111) layers to examine the interface of this material structure. We
considered Ni(111)/hBN/Ni(111) with a slab with three Ni atomic layers to
determine the exact atom arrangement at the interface. The density functional
theory calculations for 36 stacking arrangements, which are doubled with
respect to the magnetic alignment of slabs in an anti-parallel configuration
(APC) and parallel configuration (PC), revealed that the number of formed weak
chemical bonds, in the pd-hybridization between the N and Ni atoms, is
decisive. A maximum of two pd-hybridization bonds stabilized the structure,
with APC proving to be the most favorable magnetic alignment, in line with the
results of previous experimental studies. In the lowest energy state, an
induced magnetic moment at an N site appears when N is moved closer to one of
the Ni atoms. Interestingly, the moment direction is switched by the position
of the N layer in the resulting bi-stable state with electrical polarization
when APC is chosen. The transmission probability calculation of Ni/hBN/Ni
having the determined interface structure at the center of the junction
exhibits a spin-filtering effect where the spin-polarized current is controlled
by the electric field when a field-induced reversal of the polarization is
realized.
