Determination of the Exact Symmetry of the Pairing State in Sr2RuO4

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9974327LiuExperimental evidence for an unconventional (e.g. an odd parity (spin-triplet or p-wave)) pairing state in Sr2RuO4 has been growing. Such a system is the only known layered perovskite superconductor (Tc = 1.3 - 1.5K) that does not contain copper. This GOALI program brings together researchers from Penn State, IBM, JPL, and Kyoto University to carry out definitive experimental work that will address some key issues on this exciting new material. The main thrust is to determine the parity (even or odd) of the pairing state in Sr2RuO4 through phase-sensitive experiments on single-crystal-based structures using a scanning SQUID probe. In/Sr2RuO4 (or Pb/Sr2RuO4) junctions will be studied to further our understanding of Josephson coupling between a conventional s-wave and an unconventional superconductor. Au/Sr2RuO4 (or Ag/Sr2RuO4) metallic contacts will be used to search for novel surface-bound states associated with the Andreev process. Tunneling measurements on superconducting single crystals of Sr2RuO4 which are aimed at the understanding of the mechanism of superconductivity in this material will be continued to determine the energy gap of Sr2RuO4. In carrying out this work, scientists at Penn State, IBM, and JPL will be able to exchange ideas in a collaborative environment and be actively involved in the training of graduate students at all stages. Students in turn will have the opportunity to gain first hand experience working in very different settings including academic, industrial, and NASA research laboratories. This environment will provide them with a broader perspective when planning their future careers.%%%Recently Sr2RuO4, the only known layered perovskite superconductor (Tc = 1.3 - 1.5K) that does not contain copper, has attracted much attention in the superconductivity research community. In particular, experimental evidence for an unconventional, likely odd-parity (spin-triplet or p-wave) pairing state found in Sr2RuO4 has generated much excitement on this new superconducting material. The goals of this GOALI program are to determine the exact symmetry of the superconducting pairing state in Sr2RuO4 through phase sensitive and tunneling experiments and to study the Josephson coupling between an unconventional and a conventional s-wave superconductor. In carrying out these research activities, a productive, long-term partnership between Penn State, IBM, and JPL will be established to train students for our future generation of scientists and engineers. Students in turn will have the opportunity to gain first hand experience working in very different settings including academic, industrial, and NASA research laboratories. Such an environment will provide them with a broader perspective when planning their future careers. This GOALI project is supported jointly by the Division of Materials Research (Condensed Matter Physics Program) and the Directorate for Mathematical and Physical Sciences Office of Multidisciplinary Activities (MPS/OMA).***