What are magnetic isolators

Novel conductor for magnetic fields

Electromagnetic waves can be transmitted over long distances, for example using radio technology or fiber optic cables. This was previously not possible with static - i.e. temporally unchangeable - magnetic fields, because their strength decreases rapidly with the distance from the source. An international team of physicists has now developed and tested in the laboratory a new type of conductor that can transport magnetic fields over any great distance. The range of possible applications ranges from spintronics to quantum computers, report the researchers in the journal "Physical Review Letters".

Model of a conductor for magnetic fields

“Our theoretical considerations have shown that a material for conducting magnetic fields must have extremely anisotropic properties,” says co-author Oriol Romero-Isart from the Institute for Quantum Optics and Quantum Information at the Austrian Academy of Sciences. The material should therefore be particularly permeable to magnetic fields in one direction of propagation, but shield the magnetic transmission perpendicular thereto. Since no natural material has these extreme properties, the physicists developed a type of magnetic hose: They encased a cylinder made of ferromagnetic material with a superconductor, which is a perfect magnetic insulator.

The researchers' calculations had shown that such a structure made up of alternating layers of ferromagnets and superconductors can transport up to 90 percent of a magnetic field over any distance. Two layers should be enough to transfer up to 75 percent of the magnetic field. The team then implemented this theoretical concept in the laboratory. It encased a ferromagnet made of iron and cobalt with the high-temperature superconductor yttrium-barium-copper oxide and tested the arrangement in an experiment. “Despite the sub-optimal technical equipment, we were able to show that a static magnetic field can be conducted very well through the material,” says team member Alvaro Sanchez from the University of Barcelona.

The new method could, for example, be used in future quantum technologies, where static magnetic fields couple quantum bits with one another. However, applications in spintronics, which use the magnetic moment of the electron for information processing, are also possible.