Electronic Structure, Magnetic Order and Interlayer Magnetic Couplings in Metallic Superlattices

Abstract

The general trends for the electronic structure of perfect model superlattices AmBn are calculated using a real-space tight-binding model. The magnetic moments distribution and the interlayer magnetic couplings between ferromagnetic layers Am (A=Fe or Co) coupled by non-magnetic (B=V or Ru), nearly ferromagnetic (B=Pd) or antiferromagnetic (B=Cr) spacer layers Bn are obtained as a function of the spacer thickness n. In a first part, we present the model we used for the calculation and the crystallographic structure of the considered superlattices (Fe/V, Fe/Cr, Co/Ru and Co/Pd). These considerations will be applied to the non-magnetic and nearly ferromagnetic cases to derive general trends for the magnetic interlayers couplings. In a second part, we apply the method we presented previously to the superlattices with an antiferromagnetic spacer (Fe3Crn). Using first a “d” band calculation we show that the interlayer coupling energy can be understood in terms of a strong interfacial antiferromagnetic coupling and of a constrained magnetic wall in the Cr layer giving a rapidly oscillating coupling energy. An extension of the previous calculation taking into account the “spd” hybridization does not affect the previous conclusion. Finally we examine the distribution of magnetic moments and the stability of tilted antiferromagnetic Cr layers and we find that this magnetic structure is nearly degenerate with the collinear antiferromagnetic arrangement.