Unexpected magnetic coupling oscillations for L10−MnGa/Co(Fe) films induced by quantum wells

Exchange magnetic coupling interactions between $L{1}₀\text{-MnGa}$ and ultrathin Co (Fe) films were studied by first-principles calculations. An unexpected oscillation of magnetic coupling was observed by varying the thickness of Co or Fe layer. Moreover, the coupling types are different for Co and Fe with $L{1}₀\text{-MnGa}$. The magnetic coupling maintains the ferromagnetic interaction for $L{1}₀\text{-MnGa}$/Fe, even if the thickness of Fe layer varies. Interestingly, a change from ferromagnetic to antiferromagnetic couplings appears alternately for $L{1}₀\text{-MnGa}$/Co till Co thickness is up to 11 atomic layers. The coupling oscillations were attributed to the quantum well states formed in the Co (Fe) films. The orbital characters of the quantum well states were analyzed. Our results are useful to further understand the magnetic coupling interactions and design new magnetic nanostructures.