Scientists from Zhejiang University have created an invisibility cloak that can shield magnets from nearby magnetic fields. While magnets typically either attract or repel each other when they are brought into proximity, this new device prevents this process not by demagnetizing them, but by simply hiding them.
The device is a bilayer cloak that is designed from metamaterials, which are man-made materials that possess recurring patterns, and works by manipulating electromagnetic waves. Each bilayer cloak possesses a spherical structure with a superconducting inner shell and a ferromagnetic outer shell.
With opposing magnetic behaviors, these shells have the opposite effects on external magnetic fields, as the inner shell repels while the outer shell attracts. The scientists took advantage of this unique design and were eventually able to tweak the material concentrations in a way that they completely cancelled 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 invisibility cloak provides plenty of potential for various applications, including protecting organisms from magnetic fields and allowing magnetic objects to pass through metal detectors unnoticed.
"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 device is the latest created in studies that are focusing on creating invisibility cloaks, which HNGN previously reported on here and here.
The study was published in the Nov. 24 issue of the journal Nature Communications.
