University of Cambridge, CC-BY. Superconductors can levitate magnets by expelling magnetic fields, and can also trap them.

The record for the powerful magnetic field trapped by a superconductor has been broken. Once this would have been an unremarkable event, with records falling frequently, but this was the first time in eleven years progress has been made.

Superconductors are defined by their ability to conduct electricity with no resistance at all. They also affect magnetic fields, but their superconductivity is sensitive both to warm temperatures and to large magnetic fields.

The record field of 17.2 Tesla was set in 2003, and despite many attempts the record stood until Professor David Cardwell announced in Superconductor Science and Technology that his team at Cambridge University had achieved a field of 17.6T.

“High” temperature superconductors, ones that work above the boiling point of liquid nitrogen (-196°C) are made of metal oxides, but we have a poor understanding of which metal combinations will work best, making for a lot of trial and error. The record was set with 25mm grains of gadolinium boron carbon oxide (GdBCO) doped with silver. These were placed between thin sheets of copper oxide and had their microstructure modified to maximize field carrying capacity.

If sufficiently large fields can be reliably contained the potential is enormous. Superconductors are already used in MRI scanners and mass spectrometers among other scientific equipment. It is hoped they can be put to use creating smart grids and in maglev trains and new ways to store electricity. "There are real potential gains to be had with even small increases in field,” says Cardwell.

In addition to the field strength Cardwell is excited by the relatively easy manner in which the materials were made, saying, “In order to see bulk superconductors applied for everyday use, we need large grains of superconducting material with the required properties that can be manufactured by relatively standard processes." 

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