Frustrated Magnets Found to be More Unusual than Some Expected

[Guest_Jim_*]

If you heat a magnet up enough, it will lose its magnetism, but cooling a magnet should not remove that property. For some materials however, magnetism does disappear at temperatures near absolute zero, and these are called frustrate magnets. Due to this lack of magnetism, many believe that the Hall Effect, which relates to magnetism, would not exist at these temperatures, but some thought otherwise, and now researchers at Princeton University have confirmed it.

The Hall Effect is the deflection of a current of charge carriers, electrons, in a conductor by an external magnetic field. As a frustrated magnet contains neutral, non-charged particles at low temperatures, the Hall Effect seemingly would not work, but at these temperatures quantum mechanics reigns and expectations can mean very little. To test this, the researchers needed a frustrated magnet, to cool it to 0.5 K, and to be able to resolve temperature differences between opposite edges of the crystal. It was not easy to achieve, but the researchers succeeded and put a heat current through the crystal, which is analogous to an electrical current at these temperatures. When they then applied a magnetic field perpendicular to the current, they observed the current deflecting, just like the Hall Effect would suggest.

This research opens up some interesting possibilities, including potentially a new understanding of high-temperature superconductors. Some of these materials may rely on a particle called the spinon, the proposed carrier for heat currents in quantum systems, and this research may lead to a means of discovering it.

Source: Princeton University