Scientists at ETH Zurich have developed a palm-sized superconducting magnet that produces magnetic fields up to 42 Tesla, matching the power of massive laboratory behemoths. This breakthrough uses commercially available materials and requires minimal power, potentially making advanced magnetic technologies more accessible. The innovation aims to enhance nuclear magnetic resonance techniques for molecular analysis.
Strong magnets are essential in fields like MRI imaging, particle accelerators, and nuclear fusion, but the most powerful ones, made from superconductors, are typically enormous and energy-intensive. Alexander Barnes and his team at ETH Zurich in Switzerland have changed that by creating a compact superconducting magnet measuring just 3.1 millimetres in diameter.
The device is built by coiling thin tape of a ceramic material called REBCO, which superconducts at extremely low temperatures. When electric currents pass through these coils, they generate strong magnetic fields. The researchers purchased the REBCO tape from a commercial supplier and iterated through over 150 designs. As Barnes explained, “Our strategy was to develop and embrace a ‘fail often and fail fast’ approach.”
Their final design features either two or four pancake-shaped coils, achieving field strengths of 38 Tesla with two coils and 42 Tesla with four. For context, a typical fridge magnet produces less than 0.01 Tesla, while the world's strongest steady-field magnets reach about 45 Tesla but weigh many tonnes and consume up to 30 megawatts of power. In contrast, the new magnet is smaller than a hand and uses less than 1 watt.
The team's goal is to apply this magnet to nuclear magnetic resonance (NMR), a technique for determining molecular structures in drugs and industrial catalysts. Currently, NMR is limited by the size and cost of required magnets, but this compact version could broaden access for chemists. The researchers have started testing it in an NMR setup.
Mark Ainslie at King’s College London praised the achievement: “Producing magnetic fields above 40 Tesla traditionally requires very large and expensive facilities, so achieving similar field strengths in such a compact device using superconducting tapes is significant.” He added, “It suggests that extremely high-field magnets could become more accessible to a wider range of laboratories in the near future.” However, challenges remain, including ensuring field uniformity and controlling the coils' electromagnetic behavior.
The work is detailed in Science Advances (DOI: 10.1126/sciadv.adz5826).
