Magnetostriction in AlFe2B2 at 25 T Measured by X-Ray Diffraction

Published January 25, 2022

X-ray source (green arrow) with evacuated X-ray beam tunnel (blue arrow) leading to the two-meter-tall 25T Florida Split Helix Magnet (red arrow).

Alexey Kovalev and Alexey Suslov, National MagLab

Using X-ray diffraction, scientists can now detect atoms themselves moving further apart or closer together in high magnetic fields, giving science a crystal clear view of nature.

What did scientists discover?

Magnetostriction is a property of ferromagnetic materials (or materials that are attracted to magnets). Magnetostriction causes a shape change in response to an applied magnetic field. Anisotropic magnetostriction in ferromagnetic AlFe₂B₂ was investigated using an X-ray diffractometer (XRD) in the 25T Florida Split Helix Magnet.

Why is this important?

Scientists have been attempting to peer into the inner workings of nature for thousands of years. Typically, when scientists measure magnetostriction, they measure changes in length on the outside of a material and infer what is happening at the atomic level.

Magnetostrictive materials can convert electromagnetic energy into mechanical energy and vice-versa and can be used to create sensors that measure magnetic field or detect a force. Furthermore, repeated mechanical cycling can induce fatigue, which must be understood to avoid premature material failure. This experiment demonstrates the utility of the XRD system available at the MagLab to explore magnetostrictive materials. Thermodynamic relationships for magnetostriction are estimated based on a Landau model that agrees with the experimental results. This approach is readily applicable to a wide range of other materials and a user community is being developed.

Who did the research?

S. Sharma¹, A. E. Kovalev¹, D. J. Rebar¹, D. Mann², V. Yannello³, M. Shatruk², A. V. Suslov¹, J. H. Smith¹, and T. Siegrist^1,4

¹National High Magnetic Field Laboratory; ²Florida State University; ³University of Tampa; ⁴FAMU-FSU College of Engineering

Why did they need the MagLab?

The 25T Florida Split Helix Magnet is a world-unique resistive magnet that features four large ports with direct line-of-sight access to the sample at the center of the magnet. The combination of the XRD system and this magnet enables users to explore the structure of materials at magnetic fields unavailable to X-ray sources elsewhere.