Nanorod composites increase current capacity of HTSCs

17 Jun 2002

In the presence of large magnetic fields bundles of magnetic flux lines within high-temperature superconductors (HTSC) begin to move about, causing energy dissipation and sometimes even the loss of the superconducting state. In an effort to pin the flux bundles in place, Harvard scientists Peidong Yang and Charles Lieber incorporate tiny defects in the form of magnesium oxide nanorods in their HTSC samples.

The use of the nanorods increases the critical current-- the maximum allowable current-- by factors of up to 10 or more, the researchers reported in the recent edition of Science. The improvement in current density is highest for large fields and higher temperatures. Defects have been used before to control flux motion, but in previous experiments the defects were created by the use of heavy-ion or proton irradiation, a process which would be cumbersome if applied to commercial processing.