The so-called 'antimagnet' could protect a ship's hull from mines that detonate when a magnetic field is detected, or allow patients with pacemakers or cochlear implants to use medical equipment.
Less happily, though, it could also be used by criminals to dodge security systems in airports and shops.
"The ideas of this device and their potential applications are far-reaching; however it is conceivable that they could be used for reducing the magnetic signature of forbidden objects, with the consequent threat to security," says Professor Alvar Sanchez of the Universitat Autònoma de Barcelona.
"For these reasons, this research could be taken into account by security officials in order to design safer detection systems and protocols."
The inner layer of the anti-magnet consists of a superconducting material that would function to stop a magnetic field from leaking out.
This, however, would distort an external magnetic field placed over the cloak, making it detectable. The device will therefore need to be combined with several outer layers of metamaterials with varying levels of magnetic field permeability, to correct this distortion and leave the magnetic field undisturbed.
The researchers demonstrated the feasibility of the cloak using computer simulations of a ten-layered cylindrical device cloaking a single small magnet.
They also showed that the cloak could take on other shapes and function when the cylinder was not fully enclosed, making applications for pacemakers and cochlear implants feasible, as they require wires to connect to other parts of the body.
"We indeed believe, and hope, that some laboratories could start constructing an antimagnet soon. Of the two components, superconductors are readily available, for example in cylindrical shape, and the key point would be to make the magnetic layers with the desired properties," says Professor Sanchez.
"This may take a bit of work but in principle the ingredients are there."