The magnetoelastic properties of iron nitride indicate the potential for flexible spintronics

The field of Spintronics, which integrates electron charge and spin properties to develop electronic devices that increase functionality and energy efficiency, has expanded into new applications.

Beyond current technologies such as hard disk drive readheads and magnetic random access memory (MRAM), researchers are currently investigating flexible spintronics for use in wearable devices and sheet type sensors.

In these applications, it is essential to detect small changes in mechanical stress due to electrical resistance modulation. This requires controlling not only the materials with important magnetoresistance effects, but also the magnetoresistive properties.

The researchers systematically studied the magnetoelastic properties of Fe4n and its substitutional variants, Fe4-Xmnxn and Fe4-yycoyn. These materials, composed of widely available elements, were examined for the potential of flexible spintronics.

The findings are published in the journal communications materials.

High-quality single crystal nitride films were manufactured on strontium titanate (001) substrates, and measurements of magnetic strain in the (100) direction revealed negative magnetic positioning of -121 ppm of Fe4n.

This value is in the same order as the Fe-GA alloys known for their magnetic orbital characteristics. Additionally, by varying the cobalt content of Fe4-Iycoyn, the team observed a positive magnetic contraction of +46 ppm at Fe2.3Co1.7N.

To understand the mechanisms behind this adjustability, researchers analyzed the relationship between magnetoelastic properties and other magnetic properties such as saturation magnetization, magnetic anisotropy, and magnetic damping.

This study found a strong correlation between magnetic damping and magnetoelastic behavior. Further comparisons with first-principles calculations suggested that the Fermi level density of states of d-electrons play an important role in determining both properties.

This insight provides a pathway to further refine magnetoelastic properties, which could lead to improved material performance in flexible spintronic applications.

“By demonstrating that nitrogen materials exhibit both spitronic and magnetoresistive properties, we offer a new perspective on material selection for flexible spitronic devices,” said Keita Ito, assistant professor at Tohoku University’s Materials Institute (IMR).

“Understanding how some magnetic properties are interrelated will allow us to design highly responsive strain sensors in the future.”

In the future, the research team aims to manufacture magnetoresistive devices using ferromagnetic nitride films on flexible substrates. This allows for testing the effectiveness of these materials in detecting mechanical stresses with high sensitivity.

Iron nitride-based materials are made up of elements that minimize environmental impact and are not affected by resource shortages, providing a promising direction for the development of low-cost, large, flexible sensor technologies.