Sometimes taking on those hands-on type of research jobs pays off really well. Professor Harsh Deep Chopra and professor Manfred Wuttig learned this when they took certain iron-based alloys, heated them for half an hour at 760 degrees Celsius, and then quickly cooled them down, and ended up with a completely transformative breakthrough that not only has the potential to both displace existing technologies, but also to create entirely new applications.
The two professors, from the Temple University and the University of Maryland, are responsible for developing a new class of magnets. These non-Joulian magnets, that do not act as regular magnets, revolutionizes the 175 year old concept of “Joule Magnetostriction”, which was a way to characterize how magnets responded when placed in a magnetic field, established in 1841 by physicist James Prescott Joule.
“We have discovered a new class of magnets, which we call ‘Non-Joulian Magnets’, that shows a large volume change in magnetic fields,” Chopra explains. “Moreover, these non-Joulian magnets also possess the remarkable ability to harvest or convert energy with minimal heat loss.”
With the new approach, the researchers discovered that the thermally treated magnets when used as actuators, spontaneously expand in all directions, whereas it’s always been commonly known that regular magnets can only respond in one direction, due to not expanding in volume, making applications large and not so very efficient.
At a microscopic level, the new magnets contained cellular-like structures never seen before, and it is their response that constitute the very heart of the non-Joulian magnetostriction.
Chopra runs the Materials Genomics and Quantum Devices Laboratories at Temple’s College of Engineering and is chair of mechanical engineering at Temple, while Wuttig is a professor of materials science and engineering at Maryland. They published their exclusive findings in the May 21st issue of the journal Nature.
The new possibilities opening before the science community seems endless; the magnets could be used in all kinds of areas: as ultra-low thermal signature actuators for sonars, as compact micro-actuators for biomedical, aerospace, robotics, automobile and space applications. Their characteristics are so energy efficient that they can be used for a new generation of actuators and sensors that will have hardly noticeable heat signatures.
As if this is not enough, the new magnets will be much cheaper and a lot easier to make than alloys used today, which are based on materials that are rare on Earth.
Thomasz Durakiewicz, condensed matter physics program director for the National Science Foundation, shares his excitement over the discovery: “Chopra’s and Wuttig’s work is a good example of how basic research advances can be true game changers … This research has the potential to catapult sustainable, energy-efficient materials in a very wide range of applications.”
Image: Katrien Berckmoes