Substituting ruthenium for iron in iron-based superconductors tunes their properties in a very unusual way. The substitution of one element for another normally changes the crystal’s electronic structure by adding charge carriers and/or altering the size of the crystal lattice, which may induce superconductivity. High resolution angle-resolved photoemission experiments showed that neither mechanism is responsible in the case of barium–iron–ruthenium–arsenide, Ba(Fe1-xRux)2As2. The researchers speculate that ruthenium dilutes the antiferromagnetic interactions of the material when it substitutes for iron and that this causes the unexpected result. The suppression of the antiferromagnetic phase is associated with the emergence of superconductivity. This finding helps us to understand what controls superconductivity and may lead to the discovery of new superconductors.
R. S. Dhaka, C. Liu, R. M. Fernandes, R. Jiang, C. P. Strehlow, T. Kondo, A. Thaler, J. Schmalian, S. L. Bud’ko, P. C. Canfield and A. Kaminski, “What Controls the Phase Diagram and Superconductivity in Ru-Substituted BaFe2As2?”, Physical Review Letters, 2011, 107, 267002. DOI 10.1103/PhysRevLett.107.267002