The iron filings clustered around a magnetic ring and its magnetic field.
Credit: Lawrence Lawry / Getty Images
Scientists have discovered a new type of magnet hidden in a uranium compound.
The compound, USb2 (a compound of uranium and antimony), a so-called "singlet-based" magnet, is new in that it generates magnetism in a totally different way than any other magnet known to scientists.
Electrons, which are negatively charged particles, generate their own tiny magnetic fields. These fields have a "north" and "south" pole, a consequence of a property of quantum mechanics known as spin. In most objects, these magnetic fields point in random directions, canceling out each other. (That's why your body is not a giant magnet.) But in certain materials, these fields are aligned. When this happens, they create a magnetic field powerful enough to, for example, move a pile of iron around or cause a compass to point north.
Almost every known magnet in the universe works this way, from those of your refrigerator and M.R.I. machines for the magnetism of planet Earth itself. [7 Strange Facts About Quarks]
But the newly discovered singlet-based magnet works in a completely different way.
USb2 is like many other substances where the electrons inside it tend not to point their magnetic fields in the same direction, so that they can not generate magnetism by the combined force of the magnetic field.
However, the electrons in USb2 can work together to form quantum mechanical objects called "spin excitons"
Spin excitons are not like the normal particles you learned in physics and chemistry: electrons, protons, neutrons, photons, and so on. Instead, they are quasiparticles, particles that are not discrete objects in our universe, but act as if they were when groups of physical particles begin to act together in strange ways.
Spin excitons emerge from the interactions of electron groups and, when formed, a magnetic field is created.
According to a statement from the researchers responsible for the discovery of USb2, physicists had long suspected that groups of spinons could group together with their magnetic fields oriented in the same way. They called the "singlet-based" magnetism effect. The phenomenon has previously been proven in brief and fragile flashes in ultra-welded experimental scenarios, in which the strange physics of quantum mechanics is often more pronounced.
Now, physicists have shown for the first time that this type of magnet can exist in a stable way outside supercool environments.
In compound USb2, magnetic fields form rapidly and disappear almost as quickly, the researchers reported in an article published Feb. 7 in Nature Communications.
Under normal circumstances, the magnetic moments in an iron bar gradually align, without abrupt transitions between magnetized and non-magnetized states. In a singlet-based magnet, the jump between states is sharper. Spin-excitons, usually temporary objects, are stable when grouped together. And when these clusters form, they start a cascade. Like the dominoes fitting, spinning excitons fill the whole substance very quickly and suddenly, and align with one another.
This is what seems to be happening on USb2.
The advantage of this type of magnet, the researcher wrote in his statement, is that it oscillates between magnetized and non-magnetized states far more easily than normal magnets. Since many computers rely on the exchange of magnets to store information, it is possible that one day singlet-based devices will work much more efficiently than conventional magnetic configurations.
Originally published in Living Science.