Researchers at the Universitat Autònoma de Barcelona (UAB), The Institute of Materials Science of Barcelona (ICMAB-CSIC), and the ALBA Synchrotron, in collaboration with the Catalan Institute of Nanoscience and Nanotechnology (ICN2), a BIST centre, and the Universitat de Barcelona (UB), have developed a new technique to locally modify the properties of a metamagnetic material. The research opens the door to more accurate and precise control of magnetic materials and to the improvement of the architecture and capacity of magnetic digital memories.
Some memory devices that store information from smartphones and computers involve very precise control of magnetic properties at the nanoscopic scale. In certain cases, the combination of ferromagnetism (where the magnetism of all the atoms in the material points in the same direction) and antiferromagnetism (where it points alternately in opposite directions) is used to store the information. One of the materials that can show these two arrangements is the alloy of iron and rhodium (FeRh). This material presents a metamagnetic transition between these two phases at very close to room temperature, so that it can change state from antiferromagnetic to ferromagnetic simply when heated. The antiferromagnetic state is more robust and secure than the ferromagnetic one, since it is not easily altered by the presence of magnets in its proximity.
A team of researchers from the UAB, ICMAB, and the ALBA Synchrotron, along with scientists from the UB and the BIST centre ICN2 (ICN2 Magnetic Nanostructures Group), have used mechanical pressure to modify this transition and stabilise the antiferromagnetic state. Pressing the surface of the iron-rhodium alloy with a nanometer-sized needle causes the magnetic state to change in a simple and localised way. By pressing on different areas of the material, the researchers have managed to generate antiferromagnetic nano-islands embedded in a ferromagnetic matrix, a very difficult task with the current techniques available. The new technique allows for the construction of magnetic nanometric devices with much smaller structures and is much more robust and safe than the current ones. The technique can facilitate the manufacturing of magnetic memories with new architectures that improve their capacities.
More information can be found on the ICN2 website.