The rapid advancement of generative artificial intelligence has significantly increased the demand for both energy and data storage. One promising solution is the use of magneto-ionics. By applying a voltage to these materials, the ions inside them move, changing the magnetic properties.

In this study, published in ACS Nano and featured on the journal cover, the researchers focused on a system made entirely from manganese nitrides, and used neutron reflectometry on the PolRef beamline at ISIS to understand exactly how the nitrogen ions move within the different phases.

The international collaboration is led by Professor Kai Liu from Georgetown University, together with scientists at the National Institute of Standards and Technology in the US, the King Abdullah University of Science & Technology and Christy Kinane and Andrew Caruana from ISIS.

In their material, it's possible to move the nitrogen ions within the material structure by applying voltage, changing the magnetism and switching between ferrimagnetic (weakly magnetic) and antiferromagnetic (seemingly 'non-magnetic') states.

This means that data could be written when the material is in its magnetic state, then stored in its non-magnetic state, where it's immune to external magnetic interference. This creates more stable, secure memory devices whilst using less energy than conventional approaches.

“Our findings highlight the exceptional functionality and versatility of the all-nitride system," explains lead author Zhijie (Hugh) Chen. “These capabilities position this all-nitride system as a promising platform for energy-efficient and sustainable spintronic applications with the added potential for magnetic field immunity in data storage and memory."

The team has also identified ways to make the switching even faster through techniques like making thinner layers, controlled doping, and engineering deliberate defects to create easier pathways for ion movement.

“Polarized neutron reflectometry was critical for this study, as it allowed probing of depth-dependent structural and magnetic profiles along the film thickness, which provided microstructural insights on how the nitrogen ions migrated under different stimuli," said Christopher Jensen, who led the neutron studies. 

The full paper can be found at DOI: 10.1021/acsnano.5c04013