Two-dimensional ferromagnetism of 3d, 4d, and 5dtransition metal monolayers on noble metal (001) substrates

Ferromagnetism of 5d transition metal monolayers is predicted for the first time. For Ir on Ag and Au(001) magnetic moments of 0.9${\mathrm{\mu }}_{\mathit{B}}$ were found by ab initio alculations based on the full-potential linearized augmented-plane-wave method. Os is magnetic on Ag but nonmagnetic on Au. Comparing 5d magnetism with 4d and 3d results, a remarkable trend emerges: The element with the largest moment among the 3d, 4d, and 5d monolayers is shifted from Mn to Ru (isoelectronic to Fe) and to Ir (isoelectronic to Co), respectively. 4d and 5d magnetism is explained as a true-dimensional band-structure effect.