American researchers have discovered that heat can be controlled with an extremely strong magnetic field.
In an article published in the latest issue of the Nature Materials journal, a team from the Ohio State University described how a magnetic field roughly the size of a medical MRI reduced the amount of heat flowing through a semiconductor by 12 per cent.
The study is the first ever proving that the so-called acoustic phonons, elementary particles transmitting heat and sound, have magnetic properties.
"This adds a new dimension to our understanding of acoustic waves," said Joseph Heremans, a professor of mechanical engineering at Ohio State. "We've shown that we can steer heat magnetically. With a strong enough magnetic field, we should be able to steer sound waves, too."
The discovery could possibly allow controlling heat in materials such as glass, stone and plastics, which are not conventionally magnetic.
However, there is a catch. Magnets strong enough to have a measurable effect currently exist only in hospitals and research laboratories. Moreover, the heat-carrying semiconductor needs to be cooled down to minus 268 degrees Celsius, near the absolute zero, which is not practical for real-life applications.
Acoustic phonons, the particles responsible for the magnetic properties, have been described by scientists as a sort of cousin-particle to photons, particles of light. Unlike photons, acoustic phonons have so far escaped scientific scrutiny.
Professor Heremans explained that although heat and sound may seem not to have much in common at the first glance, they are, in fact, expressions of the same energy.
"Essentially, heat is the vibration of atoms," said Heremans. "Heat is conducted through materials by vibrations. The hotter a material is, the faster the atoms vibrate. Sound is the vibration of atoms, too."
The lead author of the study, Ohio State postdoctoral researcher Hyungyu Jin, said the properties are likely to be present in any solid material.