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Researchers create first magnetic diode

Technology News |
By Nick Flaherty


Working with colleagues from the Austrian Academy of Sciences and University of Innsbruck, Dr Jordi Prat-Camps (above) at the University of Sussex showed it is possible to make one magnet connect to another without the connection happening in the opposite direction. This runs contrary to the long-established theory of magnetic coupling that emerges from the four Maxwell equations.

“We have created the first device that behaves like a diode for magnetic fields,” said Dr Prat-Camps. “Electric diodes are so crucial that none of the existing electronic technologies such as microchips, computers or mobile phones would be possible without them. If our result for magnetic fields would have one millionth of the same impact as the developments in electric diodes, it would be a hugely impactful success. The creation of such a diode opens up a lot of new possibilities for other scientists and technicians to explore. Thanks to our discovery we think it might be possible to improve and the performance of wireless power transfer technologies to improve the efficiency of recharging phones, laptops and even cars.”

The research focuses on the control and manipulation of magnetic fields by the use of metamaterials. Recently Dr Prat-Camps and his collaborators have developed new tools to control magnetism including magnetic undetectability cloaks, magnetic concentrators and wormholes. By solving Maxwell’s equations analytically, the researchers showed that the reciprocity be broken down and the coupling could be made maximally asymmetric. This allows the coupling from A to B to be different from zero but from B to A it would be exactly zero. Having shown that total unidirectional coupling was theoretically possible, the team designed and built a proof-of-concept experiment which confirmed their findings.

The 3D printed model of Dr Jordi Prat-Camps’ magnetic diode which was then rotated at very high speeds. Credit: University of Sussex

“The magnetic coupling between magnets or circuits is something extremely well-known. It dates back to the seminal works of Faraday and Maxwell and it is deeply embedded into the four Maxwell equations that describe all electromagnetic phenomena. A vast majority of the technologies we rely on today are based on magnetic coupling including motors, transformers, low-frequency antennas and wireless power transfer devices. As far as we know, nobody before us thought to ask whether this symmetry could be broken and to what extent,” he said.

“If the coupling between coils is symmetric, some part of the energy can also flow in the opposite direction which can greatly reduce the efficiency of the transfer. By using a magnetic diode to prevent this backwards flow, the efficiency of the transfer could be greatly enhanced,” said team members Oriol Romero-Isart and Gerhard Kirchmair at Innsbruck.

The research is published in Physical Review Letters.

www.sussex.ac.uk


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