June 30, 2014 (HP81U – updated July 9, 2014 ).  John Durrell et al. of Cambridge University, UK, attained a record high magnetic field trapped in a bulk superconductor: 17.6 tesla, the highest reported to date.  The ability of large-grain (RE)Ba2Cu3O7 – δ, (RE = rare earth) bulk superconductors to trap magnetic fields is determined by their critical current. With high trapped fields, however, bulk samples are subject to a relatively large Lorentz force, and their performance is limited primarily by their tensile strength. Consequently, sample reinforcement is the key to performance improvement in these technologically important materials.   The author’s sample was a stack of two silver-doped GdBCO superconducting bulk samples, each 25 mm in diameter, fabricated by top-seeded melt growth and reinforced with shrink-fit stainless steel. This sample preparation technique has the advantage of being relatively straightforward and inexpensive to implement.  It thus offers the prospect of easy access to portable, high magnetic fields without any requirement for a sustaining current source (of course with the penalty of necessary continuing cryogenic cooling).  

 

The text of the Cambridge press release is accessible here.   On July 9, 2014 we published a more detailed paper highlight HP83 on these results.