Canted ferromagnetism in RuSr 2 GdCu 2 O 8

First principles calculations using the full-potential linearized augmented plane wave method including intra-atomic noncollinear magnetism have been performed to determine the magnetic structures of ${\mathrm{RuSr}}_{2}{\mathrm{GdCu}}_{2}{\mathrm{O}}_{8}.$ The magnetism clearly arises from the ${\mathrm{RuO}}_{6}$ octahedra where the moments on neighboring Ru sites order antiferromagnetically but cant perpendicular to the antiferromagnetic (AFM) axis\char22{}and so induce a weak ferromagnetism. The projected Ru moments along the AFM and FM axes result in magnetic moments of 1.16 and $0.99{\ensuremath{\mu}}_{B},$ respectively. The results are consistent with the possible coexistence of canted ferromagnetism and superconductivity in the ${\mathrm{RuSr}}_{2}{\mathrm{GdCu}}_{2}{\mathrm{O}}_{8}$\char22{}inferred from experiments.