Researchers at the University of Konstanz have developed a technique to alter the magnetic properties of materials using laser pulses, effectively transforming one material into another at room temperature. By exciting pairs of magnons in common haematite crystals, the method enables non-thermal control of magnetic states and potential data transmission at terahertz speeds. This breakthrough could allow quantum effects to be studied without extreme cooling.
A team of physicists led by Davide Bossini at the University of Konstanz has achieved a significant advance in materials science by using light to reshape the magnetic behavior of solids. The technique involves laser pulses that coherently excite pairs of magnons—quanta of spin waves—at high frequencies, influencing the frequencies and amplitudes of other magnons without generating heat. This non-thermal process changes the material's unique set of magnetic resonances, described by Bossini as its 'magnetic DNA' or 'fingerprint,' temporarily making it behave like a different material.
The discovery, published in Science Advances on October 24, 2025 (volume 11, issue 25, DOI: 10.1126/sciadv.adv4207), was unexpected. 'The result was a huge surprise for us. No theory has ever predicted it,' Bossini stated. He emphasized that 'the effects are not caused by laser excitation. The cause is light, not temperature,' allowing precise control over magnetic properties.
The method relies on widely available haematite crystals, an iron ore historically used in compasses. Unlike previous approaches limited to low-frequency magnon excitation, this directly targets high-momentum pairs, opening possibilities for terahertz-speed data storage and transmission in spintronics. It addresses data bottlenecks from AI and the Internet of Things by leveraging collective spin waves.
Furthermore, the technique suggests potential for room-temperature Bose-Einstein condensates of high-energy magnons, enabling quantum research without cooling to near absolute zero. The work was conducted within the Collaborative Research Centre SFB 1432 on fluctuations and nonlinearities in matter. Authors include Christoph Schönfeld, Lennart Feuerer, Julian Bär, and others, with contributions from Wolfgang Belzig, Ulrich Nowak, Alfred Leitenstorfer, Dominik Juraschek, and Davide Bossini.