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Strange attraction

March 23, 2015

Study shows magnets can control heat and sound.


An artist’s conception of phonons heating solid material. Taken from a series of images by Renee Ripley.

Heat, it turns out, has a magnetic personality.

As strange as it may sound, Ohio State researchers have discovered – for the first time ever -- that a magnet can control heat. 

In Joseph Heremans’ lab, a magnet a little more powerful than a medical MRI slowed the progress of heat through a material by 12 percent.

“This adds a new dimension to our understanding of acoustic waves,” said Heremans, Ohio Eminent Scholar in Nanotechnology and professor of mechanical engineering.

“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 implications of the study sound fantastical. In theory, you could stop heat from flowing through glass, stone, plastic—materials that are not conventionally magnetic—if you had a powerful enough magnet. Or you could knock a sound wave through the air the way a baseball bat knocks a ball out of the park.

Still, powerful magnets like the one used in the study aren’t found outside of hospitals and laboratories, and the experiment had to be cooled to -450 degrees Fahrenheit.


A lopsided tuning fork made of indium antinomic semiconductor, which was used in the experiment.
Photo by Kevin Fitzsimons.

So for now and the foreseeable future, it’s going to be easier to control heat with a thermostat than with a magnet.

But the discovery expands our understanding of the fundamental particles that shape our universe, Heremans said.

People might be surprised enough to learn that heat and sound have anything to do with each other, much less that either can be affected by magnets—but they can.

Heat and sound are expressions of the same form of energy, quantum mechanically speaking, he explained. Both are carried by an elemental particle known as a phonon. Like its cousin the photon, a phonon is a pseudo-particle-wave that affects objects by imparting energy. Photons carry light; Phonons carry sound and heat.

This study shows that phonons have magnetic properties, too.

Learn more about this discovery.