Scientists identify new magnetic state for future data storage

Researchers from several Japanese institutions, including the National Institute for Materials Science and Tohoku University, have experimentally demonstrated a rare magnetic state called altermagnetism in ruthenium dioxide (RuO₂) thin films. By precisely controlling the crystal orientation of RuO₂ films grown on sapphire substrates, the team was able to reveal this third fundamental class of magnetism, which combines advantages of ferromagnets and antiferromagnets. Unlike ferromagnets, altermagnets have no net magnetization, reducing interference issues in miniaturized devices, yet unlike antiferromagnets, they allow electrical readout of spin-dependent signals, making them promising for spintronics and data storage applications. The researchers used X-ray magnetic linear dichroism to map the spin arrangement and confirmed spin-split magnetoresistance, providing strong evidence of altermagnetism’s unique spin-split electronic structure. Their approach of aligning the crystal lattice uniformly was key to observing these subtle magnetic effects