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Old 08-02-2019, 10:48 AM
gary
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New type of magnet demonstrated using magnetic moments of electron-hole pairs

Researchers at New York University have announced that they have
demonstrated for the first time what is dubbed a "singlet-based magnet"
using the magnetic moment of an electron-hole pair.

Quote:
Originally Posted by Charles Q. Choi, IEEE Spectrum
A new kind of magnet, theorized for decades, may now have been experimentally proven to exist. And it could eventually lead to better data storage devices.

In a normal magnet, the magnetic moments of individual grains align with each other to generate a magnetic field. In contrast, in the new "singlet-based" magnet, magnetic moments are temporary in nature, popping in and out of existence.

Although a singlet-based magnet's field is unstable, the fact that such magnets can more easily transition between magnetic and non-magnetic states can make them well-suited for data storage application. Specifically, they could operate more quickly and with less power than conventional devices, says Andrew Wray, a materials physicist at New York University who led the research.

Now, Wray and his colleagues have discovered the first example of a singlet-based magnet that is robust—one made from uranium antimonide (USb2).

"Even though this looks like a magnet, it's profoundly different from other magnets on a microscopic scale," Wray says.

The concept for singlet-based magnets dates back to the 1960s. The temporary nature of their magnetic moments arises from a "spin exciton," which can occur when electrons collide with one another under the right circumstances. Excitons are quasiparticles made up of electrons bound to their positively-charged counterparts, known as holes. In normal excitons, the magnetic moments of the electrons and holes usually point in opposite directions and cancel each other out. In contrast, for spin excitons, the magnetic moments of the electrons and holes align the same way.
Full story here :-
https://spectrum.ieee.org/tech-talk/...als/new-magnet
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