By Josh Perry, Editor
[email protected]

Scientists at the U.S. Department of Energy Ames Laboratory (Ames, Iowa) have discovered an unknown discontinuous magnetoelastic transition in a rare earth compound composed of Europium and Indium (Eu₂In) and researchers believe that it opens the door to a new class of materials.

A giant magnetocaloric effect is associated with magnetoelastic transformation in Eu2In, which stems from Eu 5d and In 4p band overlap and their spin polarization during paramagnetic (PM) to ferromagnetic (FM) transition. (Ames Laboratory)

According to a report from Ames Lab, “Materials that possess magnetoelastic phase transitions are highly sought after for a number of developing technologies, including caloric heating and cooling systems. Materials that display this property are rare and are thought to be exclusively transition metal-based.”

The Eu₂In compound demonstrated a sharp magnetic phase transition accompanied by a large magnetocaloric effect and no hysteresis. Researchers explained the unexpected phase transition on an unusual exchange of electrons between the two elements.

Now that the researchers have observed this transition and understand its properties, they can use that knowledge to develop similar materials for applications such as magnetic refrigeration.

The research was recently published in Nature Communications. The abstract read:

“First-order magnetic transitions (FOMTs) with a large discontinuity in magnetization are highly sought in the development of advanced functional magnetic materials. Isosymmetric magnetoelastic FOMTs that do not perturb crystal symmetry are especially rare, and only a handful of material families, almost exclusively transition metal-based, are known to exhibit them.

“Yet, here we report a surprising isosymmetric FOMT in a rare-earth intermetallic, Eu₂In. What makes this transition in Eu₂In even more remarkable is that it is associated with a large latent heat and an exceptionally high magnetocaloric effect in low magnetic fields, but with tiny lattice discontinuities and negligible hysteresis.

“An active role of the Eu-5d and In-4p states and a rather unique electronic structure borne by In to Eu charge transfer, altogether result in an unusual exchange mechanism that both sets the transition in motion and unveils an approach toward developing specific magnetic functionalities ad libitum.”