This individual investigator award will provide support to a young professor at Clemson University for his research on the mixed state of type-II superconductors. In particular he will attempt to measure the amount of charge bound inside a vortex line in a type-II superconductor. Recent transport models for the mixed state of the high temperature superconductors have invoked a nonzero vortex charge as an explanation for the anomalous behavior seen experimentally. In the high temperature superconductors, the value for the vortex charge is expected to be enhanced over its value in conventional type-II superconductors. A novel technique utilizing the measurement of the mixed state thermoelectric Hall effect (Nernst Effect) will be employed in this effort. The expected sensitivity of this technique means that a null result will be as important as a finite value. The charge will be measured in the cuprate superconductors as a function of stoichiometry, temperature, and magnetic field. This research will increase our understanding of these technologically useful materials. The students working on this project will develop skills that will help them find jobs in academia, government or industrial laboratories. %%% Superconductors are materials that have zero electrical resistance and thus can carry an electrical current without loss. The technologically useful superconductors are known as type-II. These materials have what is known as a "mixed state." In the mixed state an external magnetic field is able to penetrate the superconductor in quantized (fixed) amounts, resulting in vortices. Recent theories to explain the observed anomalous behavior of the electrical and thermal transport in the mixed state of the high temperature superconductors invoke the notion of a non-zero electric charge for these vortices. The charge of a vortex has never been measured. In conventional, low temperature superconductors it would be too small. However it may be possible to measure this value in the high temperature superconductors. This individual investigator award will provide support to a young professor at Clemson University for his attempt to measure the charge bound inside a vortex in a high temperature superconductor. The project will utilize a newly developed, sensitive technique to make this measurement. The technique has enough sensitivity that even a measured value of zero for the charge will be significant and have implications for the theories of the mixed-state. This research will increase our understanding of these technologically useful materials. The students working on this project will develop skills that will help them find jobs in academia, government or industrial laboratories.
