Suppression of spin density wave by isoelectronic substitution in PrFe1-xRuxAsO

We have studied the effects of the isoelectronic substitution of Ru for Fe in polycrystalline samples of the spin density wave (SDW) material PrFeAsO. Crystal structures from powder X-ray diffraction at room temperature and transport properties from 2 to 300K are reported. The SDW is completely suppressed upon Ru substitution. The distortion of the tetrahedral coordination environment of the transition metal site increases as the Ru concentration increases, which may be related to the absence of superconductivity above 2 K. Band structure calculations show that the larger size of Ru 4d orbitals is primarily responsible for the suppression of magnetism as Ru is substituted into the Fe layer. The experimental results indicate that long-ranged magnetic order of Pr moments is suppressed at Ru concentrations as low as 10%. (C) 2009 Elsevier Inc. All rights reserved.