Tunable coupling in CrO2 via RuO2 layers

Theoretical calculations of the magnetic structure of CrO2-RuO2 interfaces and multilayer structures are presented. The antiferromagnetic coupling between Ru ions and neighboring Cr ions in such interfaces is explored both for contiguous layers of CrO2 and RuO2 and for Cr layers separated by RuO2 spacers. The Fermi surface of the RuO2 spacer is calculated and k(F)(100) is utilized to determine the oscillatory behavior of the interlayer exchange coupling as described by Bruno [Phys. Rev. B 52, 411 (1995)]. The first-principles calculations are found to be qualitatively consistent with the Bruno theory, which suggests that CrO2-RuO2 layered structures could be designed to give the desired magnetic ordering between CrO2 layers given sufficient control over the composition and roughness of the deposited material. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3068417]