Density functional study of CaN monolayer on Si(001)

• Ab-initio studies are done on various structures of CaN monolayer on Si (001).
• The lowest energy system was found to be the N-top configuration interface, while the highest spin polarization was observed in the Ca-hollow termination.
• Both Ca-hollow and N-top are unstable toward a nonmagnetic rock–salt CaN monolayer on silicon surface.
• Realization of a magnetic CaN/Si (001) interface likely requires some buffer layer on silicon surface, prior to the thin film deposition.

In this work, the first-principles computations are performed to study the structural and magnetic properties of CaN/Si(001) interface. Bulk CaN in the zinc-blende (ZB) structure is argued to be an ionic magnetic compound with a total spin moment of 1 μB per formula unit, originated from the p electrons of N ions. Various interface configurations of a ZB CaN monolayer on Si (001) surface are investigated and the lowest energy and the highest spin polarized interfaces are extracted. Then the minimum energy path between the lowest energy and the highest spin polarized interfaces are calculated by using the nudged elastic band method and it is argued that both these systems are unstable toward a nonmagnetic interface with a rock–salt arrangement of Ca and N atoms.