Antiferromagnetic materials have broad application prospects in the fields of information processing and memory chip technology. According to the latest issue of Nature magazine, a research team from the Massachusetts Institute of Technology in the United States has achieved magnetic state transition in antiferromagnetic materials using only light, creating a new and persistent magnetic state. This technology provides researchers with powerful tools for controlling magnetism, which can help design faster, smaller, and more energy-efficient memory chips. Antiferromagnets are composed of atoms with alternating spin directions, with each atom having a spin direction opposite to that of its adjacent atoms. This order of up, down, up, and down basically cancels out spin, making the total magnetization of the antiferromagnetic material zero and thus unaffected by any magnetic force. If antiferromagnetic materials can be used to make memory chips, data can be "written" into the microscopic regions of the material, namely magnetic domains. In a given magnetic domain, a certain configuration of spin direction (e.g. top bottom) represents the classical bit "0", while another configuration (bottom top) represents "1". Writing data on such a chip can resist interference from external magnetic fields. Due to the stability of magnetic domains, antiferromagnets can be integrated into future memory chips, resulting in less energy consumption, smaller space occupation, and more data storage and processing. However, a major obstacle to applying antiferromagnetic materials to storage technology is how to reliably control the antiferromagnetic material to transition from one magnetic state to another. This time, the team used terahertz lasers to directly stimulate atoms in antiferromagnetic materials. The oscillation frequency of the laser is adjusted to match the natural vibrations between the atoms of the material, thereby changing the balance of atomic spin and transforming it into a new magnetic state. The material used is FePS3- a material that transforms into an antiferromagnetic phase at a critical temperature (approximately 118K). They placed the synthesized FePS3 sample in a vacuum chamber and cooled it to a temperature of 118K or below. Then, they let a beam of near-infrared light pass through the organic crystal, converting the light into terahertz frequencies and generating terahertz pulses. Afterwards, they aimed this beam of terahertz light at the sample. In multiple repeated experiments, the team observed that terahertz pulses successfully switched materials that were originally antiferromagnetic to a new magnetic state. This transformation is unexpectedly long-lasting, even lasting for several milliseconds after the laser is turned off. (New Society)