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Perpendicular magnetic tunnel junctions in the next-generation magnetic memory using current induced magnetization switching will likely rely on a material design that can enhance the perpendicular magnetic anisotropy of heterojunctions containing only light elements. Using first-principles calculations, we investigated the effect of compressive and tensile strain on the perpendicular magnetic anisotropy of light element heterostructures of Co films, Co/graphene, and Co/BN. We found that the perpendicular magnetic anisotropy of Co/graphene is greatly enhanced compared to the Co films, while that of Co/BN is reduced compared to the Co films. In addition, tensile strain can further enhance perpendicular magnetic anisotropy of Co/graphene and Co/BN heterojunctions by 48. 5% and 80. 8%, respectively, compared to the unstrained systems. A density of state analysis, combined with layer and orbital magnetic anisotropy contributions obtained from a second-order perturbation theory of the spin-orbit coupling, reveals that the tensile strain effect arises from the increase of the hybridization between same spin dₗₘ and dₗ^{2-y^2} states of the surface Co film. Our results suggest that strain engineering is an effective approach to enhance the perpendicular magnetic anisotropy of light element heterostructures.
Yang et al. (Wed,) studied this question.