A new study states that magnets can be used to control both heat and sound. Researchers from the Ohio State University have discovered how to control heat and sound with a magnetic field from powerful magnets.
Joseph Heremans, professor of mechanical engineering at the Ohio State University, and the lead author of the study, said, “This adds a new dimension to our understanding of acoustic waves. We have shown that we can steer heat magnetically. With a strong enough magnetic field, we should be able to steer sound waves, too.”
For their study, the researchers analyzed semiconductors, which were cooled to 450 degrees below zero Fahrenheit before being exposed to seven-Tesla magnets, similar to those found in laboratories and hospitals. Indium antimonide was used to create a semiconductor shaped like a minuscule tuning fork, with one tine having a diameter of one-sixth of an inch, and the other just one-quarter that size.
The researchers found that phonons going through the narrow side slow down due to collisions, compared with those in the other half of the fork. The researchers then recorded the temperature changes in each tine, and the difference in speed between the two sides was recorded.
They found that when the magnet was active, flow of thermal energy through the larger side was found to be 12% lower than when the magnetic field was shut off.
“Essentially, heat is the vibration of atoms. Heat is conducted through materials by vibrations. The hotter a material is, the faster the atoms vibrate. We believe that these general properties are present in any solid,” added Heremans.
The researchers believe that the findings could help to control heat in nonmagnetic materials, such as wood, plastic and concrete. However, materials that exhibit magnetic properties, including iron, would not be affected by phonons since they transfer a great deal of heat through electrons, which will overwhelm the effect.
The findings were published in the Nature Materials journal.