Mobile-Menu

Cooling Experiment Reveals Mysterious Properties of Sound Waves

Von Sebastian Gerstl 4 min Lesedauer

Anbieter zum Thema

MEV Elektronik Service GmbH
Caltest Instruments GmbH

Researchers at The Ohio State University have discovered how to control heat with a magnetic field. The study is the first to prove that acoustic phonons have magnetic properties.

Joseph Heremans, Ohio Eminent Scholar in Nanotechnology, holds an artist’s rendering of a phonon heating solid material. (Artist’s rendering by Renee Ripley, Photo by Kevin Fitzsimons, The Ohio State University)
Joseph Heremans, Ohio Eminent Scholar in Nanotechnology, holds an artist’s rendering of a phonon heating solid material.
(Artist’s rendering by Renee Ripley, Photo by Kevin Fitzsimons, The Ohio State University)

Joseph Heremans, Ohio Eminent Scholar in Nanotechnology and professor of mechanical engineering at Ohio State, says regarding the discovery: “This adds a new dimension to our understanding of acoustic waves. We’ve shown that we can steer heat magnetically. With a strong enough magnetic field, we should be able to steer sound waves, too.”

People might be surprised enough to learn that heat and sound would have anything to do with each other, much less that either can be controlled by magnets, Heremans further acknowledged.

But both are expressions of the same form of energy, quantum mechanically speaking. So any force that controls one should control the other.

“Essentially, heat is the vibration of atoms,” he explained. “Heat is conducted through materials by vibrations. The hotter a material is, the faster the atoms vibrate."

“Meanwhile, sound is the vibration of atoms, too,” he continued. “It’s through vibrations that I talk to you, because my vocal chords compress the air and create vibrations that travel to you, and you pick them up in your ears as sound.”

The name “phonon” sounds a lot like “photon.” That’s because researchers consider them to be cousins: Photons are particles of light, and phonons are particles of heat and sound. But researchers have studied photons intensely for a hundred years - ever since Einstein discovered the photoelectric effect. Phonons haven’t received as much attention, and so not as much is known about them beyond their properties of heat and sound. This study shows that phonons have magnetic properties, too.

“We believe that these general properties are present in any solid,” said Hyungyu Jin, Ohio State postdoctoral researcher and lead author of the study.

The implication: In materials such as glass, stone, plastic - materials that are not conventionally magnetic - heat can be controlled magnetically, if you have a powerful enough magnet. The effect would go unnoticed in metals, which transmit so much heat via electrons that any heat carried by phonons is negligible by comparison.

There won’t be any practical applications of this discovery any time soon: 7-tesla magnets like the one used in the study don’t exist outside of hospitals and laboratories, and the semiconductor had to be chilled to -268 degrees Celsius - very close to absolute zero - to make the atoms in the material slow down enough for the phonons’ movements to be detectible.

That’s why the experiment was so difficult, Jin said. Taking a thermal measurement at such a low temperature was tricky. His solution was to take a piece of the semiconductor indium antimonide and shape it into a lopsided tuning fork. One arm of the fork was 4 mm wide and the other 1 mm wide. He planted heaters at the base of the arms.

Artikelfiles und Artikellinks

(ID:43330407)

Jetzt Newsletter abonnieren

Verpassen Sie nicht unsere besten Inhalte

Mit Klick auf „Newsletter abonnieren“ erkläre ich mich mit der Verarbeitung und Nutzung meiner Daten gemäß Einwilligungserklärung (bitte aufklappen für Details) einverstanden und akzeptiere die Nutzungsbedingungen. Weitere Informationen finde ich in unserer Datenschutzerklärung. Die Einwilligungserklärung bezieht sich u. a. auf die Zusendung von redaktionellen Newslettern per E-Mail und auf den Datenabgleich zu Marketingzwecken mit ausgewählten Werbepartnern (z. B. LinkedIn, Google, Meta).

Aufklappen für Details zu Ihrer Einwilligung

Weiterführende Inhalte