By slipping iron between two nitrogen atoms in a lithium matrix, researchers are able to trick iron into having magnetic properties like those of rare-earth elements.Rare-earth magnets are stronger than typical iron-based magnets and have high magnetic anisotropy, meaning they are easily magnetized in one particular direction. Rare-earth elements are in high demand, difficult to find in large concentrations, and costly to mine. Iron, in contrast, is abundant and cheap. If iron can be made to behave like a rare-earth element, strong permanent magnets could be made without rare earths. Interestingly, lithium and iron are not known to like to mix together. Researchers discovered that adding nitrogen to lithium first and then adding iron, enables iron to mix with lithium. Lithium–iron–nitride single crystals were synthesized via this new approach. Typically, a value of 1 Tesla for the magnetization field is considered a strong permanent magnet. These single crystals showed a value of more than 11 Tesla! For now, the interesting magnetic properties of the lithium–iron–nitrogen material are only observed at low temperatures.However, this material is a model system for further theoretical and experimental studies to find rare-earth magnet replacement materials.
Giant magnetic anisotropy and tunnelling of the magnetization in Li2(Li1−xFex)N