Local magnetic anisotropy analysis on manganese boride ultrathin films on transition-metal surfaces studied by first-principles calculations

We have developed a method for a local magnetic anisotropy analysis based on second-order perturbation theory. We applied our method to new two-dimensional ferromagnetic nanostructures, MnB/Ag(001) and MnB/Pd(001), using their electronic structures obtained by first-principles calculations. For understanding physical origins of magnetic anisotropy at surfaces, magnetic information considering substrate effects is required. Our method considers hybridization as overlap integrals, and as a result we successfully evaluate the MAE more accurately like in Pd-substrate systems where substrate effects are important. Our method clarifies that perpendicular magnetic anisotropy of MnB/Ag(001) is attributed to virtual transition processes between up-spin occupied states and down-spin unoccupied states, whereas in-plane anisotropy of MnB/Pd(001) comes from transition among down-spin occupied states and up-spin unoccupied states. We also discuss the detailed mechanism of exhibiting the ferromagnetic state taken MnB/Ag(001) as an example.