Magnetostriction is a property of ferromagnetic materials. This phenomenon causes the materials to expand in response to a magnetic field.
The effect causes the buzz of fluorescent lights and electrical transformers and occurs when a material’s shape and magnetic field are linked.
Recently, scientists from the University of Michigan have come up with a material that’s at least twice as magnetostrictive and cheaper than other materials. Along with computing, this new material could also lead to better magnetic sensors for medical and security devices.
Scientists developed this new material using a combination of iron and gallium.
U-M materials science and engineering professor John Heron said, “A key to making magnetoelectric devices work is finding materials whose electrical and magnetic properties are linked. And more magnetostriction means that a chip can do the same job with less energy.”
Currently used magnetostrictive materials are made from rare-earth elements. These elements are too scarce and costly to be used in the quantities needed for computing devices.
In this study, scientists found a way to get high levels of magnetostriction using inexpensive materials.
Adding more gallium increases the magnetostriction of iron-gallium alloy increases. But, those increases level off and eventually begin to fall as the higher amounts of gallium begin to form an ordered atomic structure.
Scientists used a process called low-temperature molecular-beam epitaxy to freeze atoms in place, preventing them from forming an ordered structure as more gallium was added. Doing so, scientists were able to double the amount of gallium in the material, netting a tenfold increase in magnetostriction compared to unmodified iron-gallium alloys.
Heron said, “Low-temperature molecular-beam epitaxy is an extremely useful technique—it’s a little bit like spray painting with individual atoms. And ‘spray painting’ the material onto a surface that deforms slightly when a voltage is applied also made it easy to test its magnetostrictive properties.”
- Meisenheimer, P.B., Steinhardt, R.A., Sung, S.H., et al. Engineering new limits to magnetostriction through metastability in iron-gallium alloys. Nat Commun 12, 2757 (2021). DOI: 10.1038/s41467-021-22793-x