Relative stability of an on-top and an inverted Mn monolayer on Ag(1 0 0): Experiment and theory

Abstract

Mn films with a thickness of one monolayer (ML) have been deposited in ultra-high vacuum, at room temperature (RT), on a Ag(1 0 0) single crystal. Photoemission and ion scattering spectroscopy data indicate that after Mn evaporation a substantial fraction of the Mn atoms is located within the second topmost atomic layer. If the film is left at RT or mildly (60 °C) annealed, the Mn atoms tend to exchange further with Ag atoms, increasing the Mn concentration in the second atomic plane. Eventually the second atomic plane of the sample is constituted mainly by Mn atoms, whereas the first atomic layer is almost a pure Ag plane, i.e. an inverted atomic Mn ML is formed. To directly compare experiment and theory, we have performed ab initio electronic band structure calculations on the energetic stability of 1 ML of Mn on top of Ag(1 0 0) versus 1 ML of Mn covered by one Ag atomic plane. The case of a 2 ML-thick MnAg alloy is also investigated. The relation between magnetism and stability of Mn films is discussed.