Magnetic 'Invisibility Cloak' Can Protect Objects From Magnetic Fields
Now magnets too have attracted research on invisibility cloaks by scientists from Zhejiang University.
A team has created an invisibility cloak that keeps away magnets from nearby magnetic fields. If they are brought close to each other, magnets can either attract or repel each other. But this novel creation can prevent the process--not by demagnetizing them, but by just "hiding" them.
Hence, the new device is a bilayer cloak designed from metamaterials. These are man-made materials with "recurring patterns". They work by manipulating electromagnetic waves. Each cloak has a spherical structure that contains a superconducting inner shell as well as a ferromagnetic outer shell.
Hence, these shells have contrasting effects on external magnetic fields. Even as the inner shell repels, the outer one attracts.
This unique design made scientists tweak the materials in such a way that both the fields can totally cancel out the opposing effects.
"In an optimum state, these two counteractions (expelling and attracting) can be totally balanced so that their combination will have no disturbance on the external magnetic field at low frequencies," head researcher Yungui Ma told Phys.org.
The cloak has the potential for many applications, including giving protection for living things from magnetic fields and enabling the passing of magnetic things through metal detectors without giving any clues.
"Their article is a nice extension of our works on magnetic cloaks," said Alvaro Sanchez, who created the first bilayer cloak. "Their work represents another demonstration that d.c. and low-frequency regions of the electromagnetic spectrum may be some of the best cases for actual applications of cloaks. Because static and low-frequency magnetic fields are crucial in many technologies, from medicine to information technology to security, the magnetic cloaking results may have important applications in actual technologies."
The study was published in the Nov. 24 issue of the journal Nature Communications.