Magnetic properties of Ca-doped SrRuO3 from full-potential calculations

We have carried out accurate generalized-gradient-corrected fully-relativistic full-potential calculations for Sr1-xCaxRuO3 (x=0, 0.25, 0.5, 0.75, and 1) in para-, ferro-, and A-, C-, and G-type antiferromagnetic configurations. We have performed electronic structure calculations for the experimentally observed orthorhombic structure as well as the hypothetical cubic structure. Our results are analyzed with the help of total, site-, spin-, and orbital-projected density of states. The total-energy studies show that CaRuO3 stabilizes in the G-type antiferromagnetic state. The octahedral tilting owing to the relatively small radius of Ca2+ leads to weak hybridization between Ru 4d and O 2p. This weak hybridization along with exchange splitting causes a pseudogap-like feature close to the Fermi level, which should stabilize G-type antiferromagnetic ordering in CaRuO3. However, powder neutron diffraction data on CaRuO3 taken at 8 and 298 K do not show any magnetic peaks, implying that CaRuO3 exhibits a spin-glass-like state with dominant short-range antiferromagnetic interaction. The calculated magnetic ground state of Sr1-xCaxRuO3 is found to be consistent with the experimental findings. We have also calculated optical spectra as well as X-ray and ultra-violet photoemission spectra and Ru and O K-edge X-ray absorption spectra for G-type CaRuO3 and found good agreement with available experimental spectra