University of Virginia-led physics team has made a significant discovery that could introduce batches of more efficient refrigerators, heat-pumps, airport scanners, etc – all within a span of ten years. This team discovered a universal law governing the properties of metamagnets – that metal alloys can experience dramatic increase in magnetization even when a small external magnetic field is brought in the picture, say a permanent magnet or an electromagnet. The scientists observed that the magnetic effect of almost all metamagnets is non-linear. When these are placed in a magnetic field and when the initial field is doubled, the metamagnets more than double in their magnetic strength. This is huge, because now engineers have an option to harness this very energy in several applications including refrigeration.
Bellave Shivaram, a Virginia University Professor in whose Illinois-based Argonne National Laboratory the studies were conducted, stated-
We found that this nonlinear property has the same quantitative behavior in all different types of metamagnets, which is the universal law. A very useful property of this type of magnetism is in magnetic refrigeration. Magnetic refrigerators are not commonplace; they still are in the experimental stage. But they could eventually become part of everyday home appliances, from heat pumps to the refrigerators we store food in. With the new discoveries of the properties of metamagnets, they could become part of everyday home appliances within a decade or so
The study-findings have been published in several online journals (separate papers) – Review of Scientific Instruments, Physical Review B and Rapid Communications.
At present, metamagnets generate efficient cooling at very low temperatures only by employing superconducting magnets, and this makes them impractical for general refrigeration. The existing home refrigerators are high energy-consumers, they include several moving parts whicha re costly to repair, and they emit fluorocarbons in the atmosphere further adding to Global Warming. The future refrigerators which shall be using metamagnets shall have fewer moving parts and would not need refrigerants to cool, and also, they’d suck lesser electricity.
Shivaram says that in these new materials, the magnetism could be cycled on and off, thus making it possible for heat to be pumped away (similar to a heat-pump). In the present heat-pump, pressure is applied to cycle the cooling medium from liquid to vapor. In future refrigerators, magnetic materials shall be used and magnetic field shall be cycled instead. Metamagnets could find another suitable application in airport screening devices. Presently the screeners use terahertz waves to scan the materials. A screener with metamagnets shall generate terahertz waves more efficiently by converting high-powered, low-frequency radio waves into terahertz waves by using the non-linear properties of metamagnets, he said. They are still working on all possible applications where metamagnets could be useful.
Can you think of any applications where these metamagnets can come in useful? Kindly enlighten us in comments below.