Ferromagnetism in Pd thin films induced by quantum well states

We performed the first-principles density-functional calculations to investigate the magnetism of palladium films up to 21 ML (monolayer) thick, employing the highly precise full-potential linearized augmented plane-wave method. The ferromagnetic state is stable in Pd films only with particular thicknesses, 1, 4, 9, and 15 ML. While the ferromagnetism of Pd monolayer is due to band narrowing, magnetization in 4, 9, and 15 ML of Pd is obviously triggered by quantum well states, rather than by surface termination. We predicted sizable x-ray magnetic circular dichroism spectra of magnetic Pd films for experimental verifications.