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Symmetry of high tc order parameter


Research objectives and content
Recently, it appears that the order parameter in high Tc superconductors is d-wave, breaking the underlying symmetry of the material. This question cannot be settled definitively on orthorhombic materials because of the presence of chains. One needs a model high Tc compound with tetragonal symmetry and a single Cu02 layer (TSL). Amongst the several TSL compounds we selected the HgBa2CuO4+O (Hg-1201) compound for its particularly 'clean' chemical structure. We plan to perform symmetry testing experiments on this new compound such as angularly resolved tunneling and thermal conductivity in a field. These are novel experimental techniques which provide for the first time the capacity to experimentally map the superconducting gap along different crystallographic directions. We put the accent on excellent quality samples. Ist year of the project will be spent on extensive physical characterization of-the single crystals. 2nd year of the project will be spent on symmetry testing experiments. Expected results are classification of the physical properties of Hg-1201 compound as well as angular variation of the gap. Ultimately, we expect to clarify the issue of the symmetry of the order parameter in this novel compound.
Training content (objective, benefit and expected impact)
This a new held: high quality single crystals of Hg-1201 have been performed only very recently (1996-97); many leading european laboratories are currently measuring them. Strong impact of our work: it will provide new data from key experiments in the novel TSL compound Hg-1201. Training in many areas such as thin film deposition-lithography techniques, micro-mechanics and micro-manipulation, six face lithography, ion polishing is of high technological value and well adapted for an industrial position. Multiple exposure to several European laboratones collaborating on the project is particularly useful for a future research career possibly back to Greece.
Links with industry / industrial relevance (22)
The CRTBT host group, together with Demokritos, Athens, have an ongoing collaboration with CERECO SA, a greek R&D company specialized in ceramics and refractories. The present project will be part of this collaboration

Funding Scheme

RGI - Research grants (individual fellowships)


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