Search for Very High-T$_{\mathrm{c}}$ Superconductivity in Modified Compositions of Strontium Ruthenates

In 2004-2007 we discovered unusual properties in laser-processed crystals of strontium ruthenates (including resistive and magnetic transitions) pointing towards superconductivity at 200K and higher [1]. Being interested in understanding and reproducing their properties we explored their composition further. We obtained, via Auger-analysis, the presence of sulfur in the explored sample. The appearance of iron-based superconductors further enhanced our interest, since compositionally our materials turned out to be close to some of these new materials. If our reported observations [1] have been caused by superconductivity that may mean that one can get T$_{\mathrm{c}}$ as high as 200-250K or even higher with these materials at proper processing. We undertook systematic research of ceramic materials Sr$_{\mathrm{2}}$RuO$_{\mathrm{4}}$ with sulfur and other dopants. Data on resistive, magnetic and other physical properties, as well as preparation techniques are reported. [1] A.M. Gulian, V.R. Nikoghosyan, Unusual properties of laser-processed strontium ruthenates, in: T. Frias, V. Maestas (Eds.), Bulk Materials: Research, Technology and Applications, Nova Science Publishers, Inc., NY, 2010, Ch. 9 (see also arXiv: cond-mat/0509313 and cond-mat/0705.0641).