Evidence of large Dzyaloshinskii Moriya interaction at the cobalt/hexagonal boron nitride interface

Hexagonal boron nitride (h-BN) is used in 2D van der Waals heterostructures as a neutral material, often with a passivation role. However, here we show that h-BN deposited on ultra-thin Co film induces large Dzyaloshinskii Moriya interaction (DMI) and perpendicular magnetic anisotropy (PMA). Clean Co/h-BN were obtained by combining ultra-high vacuum growth and mechanical exfoliation. DMI and PMA are measured using Brillouin light scattering spectroscopy on series of samples of varying Co thickness grown on Pt or Au and covered either with h-BN or Cu. By comparing the h-BN-covered samples with their corresponding control Cu-covered samples, the effect of the Co/h-BN interface is extracted. This reveals that the Co/h-BN interface induces a large PMA and DMI comparable in strength to the largest known effects, such as those of the Pt/Co interface. This effect can be combined to that of Pt/Co in Pt/Co/h-BN films, to produce an even larger PMA and DMI. This enables the stabilisation of skyrmions in the Pt/Co/h-BN system, as was observed at room temperature with low magnetic fields. Our findings further expand the applications of h-BN, paving the way for using h-BN as functional material in the field of spintronics despite its weak spin-orbit interaction.