Seminars Archive

Superconductivity of Sr2RuO4 - Sr3Ru2O7 eutectic crystals grown by floating zone technique

Abstract
It has been more than ten years since the superconductivity in layered perovskite oxide without the presence of Cu was discovered [1]. The properties of the layered perovskite oxide Sr2RuO4 are a subject of active current investigation [2], particularly because a number of experiments as well as theoretical studies indicate spin-triplet pairing. To establish unambiguously the odd parity required for the spin-triplet pairing in Sr2RuO4, a number of tunneling and proximity effect experiments have been performed. Nevertheless, the observed current-voltage characteristics of interfaces of metal-superconductor, metal-insulator-superconductor and superconductor-insulator-superconductor junctions gave mixed results. Even if optimal quality samples have been used many problems of controlling interfaces have arisen. To circumvent this problems we pursued the possibility to grow Sr2RuO4-normal metal composite crystals with natural and clean interfaces taking advantages of the eutectic solidification process. In particular, we choose as normal metal the ruthenate metamagnet Sr3Ru2O7. We succeeded in growing Sr2RuO4-Sr3Ru2O7 eutectic crystals [3]. Here, the first results of transport measurements performed on this new system is reported. These measurements show the presence of a superconducting behaviour in the normal Sr3Ru2O7 at a distance of hundreds of microns from the superconducting Sr2RuO4 domain. These results raises new interesting questions about the physics involved in system consisting of the spin-triplet Sr2RuO4 and the metamagnet Sr3Ru2O7. [1] Y. Maeno et al., Nature 372, 532 (1994). [2] A.P. Mackenzie, Y. Maeno, Rev. Mod. Phys. 75 (2003) 657. [3] R. Fittipaldi, A. Vecchione, S. Fusanobori, K. Takizawa, H. Yaguchi, J. Hooper, R.S. Perry, Y. Maeno, J. Crystal Growth 282 (2005) 152.