Researchers from the University of Cambridge in the UK have set a new record for a trapped field at any temperature in a superconductor - materials that carry electrical currents with little or no resistance when cooled to below a certain temperature and generate a strong magnetic field.
Working with gadolinium barium copper oxide (GdBaCuO), the team managed to trap a magnetic field with a strength of 17.6 Tesla - around 100 times stronger than the field generated by a fridge magnet - inside a golf ball-sized sample of material.
This beats the previous record, held for the past decade by researchers from Japan, by 0.4 Tesla.
"The fact that this record has stood for so long shows just how demanding this field really is," said Professor David Cardwell from the University of Cambridge in a press release. "There are real potential gains to be had with even small increases in field."
Superconductors are already being used to create high-speed levitating trains and in MRI scanners, engineering tools and mineral refinement devices, and scientists are now looking to use them to store electricity in power grids, which would help manage power surges.
However, traditional superconductors only work if they’re cooled to close to absolute zero (-273°C), something that requires a huge amount of energy. Instead, engineers are focussing on high-temperature superconductors, which have next to no resistance when they’re cooled to just the temperature of liquid nitrogen (-196°C). These high-temperature superconductors are far more practical as they can be cooled down simply using widely-available and cheap liquid nitrogen.
GdBaCuO is one of these high-temperature superconductors, and using a single 25-mm-diameter sample, the researchers have been able to trap three tonnes of force inside the material, which is usually as brittle as fine china. That’s more than the amount capable of being trapped even in low-temperature superconductors. The research is published in Superconductor Science and Technology.
GdBaCuO is a type of cuprate - a material made up of sheets of copper and oxygen separate by more complex types of atoms, a press release explains. While these cuprates are high quality superconductors, they’re extremely brittle and so when researchers try to contain strong magnetic fields in them they often explode.
In order to hold the field sustainbly inside the material, the team modified the microstructure of GdBaCuO and also reinforced it with a stainless steel ring, which effectively ‘shrink-wrapped’ the single grain sample.
The team also demonstrated that creating these bulk grains of superconductors using a melt processing method can help to advance the field.
"This work could herald the arrival of superconductors in real-world applications," said Cardwell. "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."