For many years researchers have sought to discover just how many uses magnetic fields can have. To date they have become essential in quantum computing, they are vital in medical imaging, and astronomers have even used natural magnetism to amplify the signals of light from far off supernovae and galaxies so that we here on Earth can see them hundreds or thousands of light-years away. But in a new study from researchers at Ohio State University, nanotechnologists have revealed that magnetic fields can impact our lives in far more real ways-controlling heat and sound waves that exhibit magnetic properties of their own.
Publishing their results today in the journal Nature Materials, the researchers discovered a way of controlling acoustic phonons, the particles that transmit heat and sound waves, using a magnetic field only the size of a medical MRI machine. While the researchers say that people may be surprised to learn that the two very different properties of sound and heat share common origins, quantum mechanically speaking both are expressions of the same form of energy.
"This adds a new dimension to our understanding of acoustic waves" lead researcher of the study Joseph Heremans says. "We've shown that we can steer heat magnetically. With strong enough magnetic fields, we should be able to steer sound waves, too."
Considered to be cousins to photons, phonons are particles of sound and heat. For over a hundred years, since Einstein discovered the photoelectric effect, researchers have intensely studied the properties of lights revealing not only their magnetic properties, but their dual forms as well. In contrast, phonons have not been studied in depth, partly because of the fact that their properties are contingent on how they affect other materials, rather than how they act alone.
"Essentially heat is the vibration of atoms. Heat is conducted through materials by vibrations. The hotter a material is, the faster the atoms vibrate" Heremans says. "Sound is the vibration of atoms too. 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."
In the study the researchers revealed that in utilizing a strong enough magnetic field that they were able to reduce the amount of heat flowing through a semiconductor by up to 12 percent, and the researchers believe that with even stronger magnets they will be able to soon control the propagation of sound waves.
What Practical Applications Does this Study Have?
While the researchers admit that current magnet technology must advance, as the 7-tesla magnets used in the study don't currently exist outside of hospitals and laboratories, their tricky experiment may one day be able to control heat in substances that are not conventionally magnetic, such as glass, stone and plastic-though the day that this would be possibly applicable for the general public is far off.
