TRANSITION-METAL MONOLAYER OR BILAYER - FERROMAGNETISM VERSUS LATTICE-PARAMETER

Within a tight-binding scheme, monolayer and bilayer ferromagnetism is investigated. We determine the possible values of the magnetic moment versus the band filling. We point out the importance of first-order transition from a para- to ferro-magnetic state. For this reason, a large range of magnetic moment values is excluded. If only "s" bands are considered, the forbidden magnetic moment areas are limited. For systems with "d" bands, the possible values are very restricted and saturated ferromagnetism is often present. A systematic study for transition metals is presented and the critical lattice parameter for the onset of ferromagnetism is discussed. Good agreement with available experimental data is obtained.