Imagine you could change the properties of a material so that it would almost magically turn into a different material. You need neither a magic wand nor a wonder potion. The process takes place just with the help of light, which excites the magnetic states of the material. In this way, collective magnetic vibrations in the material are induced, transmitting and storing information at terahertz rates. The recipe works at room temperature, without any significant heat development. No exotic materials such as rare earths are required either, as the process was observed in naturally grown crystals, which are widely available. And to top it all off: Now imagine that you could even use the same method to exploit quantum effects – those highly sensitive processes that have so far usually been researched at low temperatures of around -270 degrees Celsius. And you could do that at room temperature with no need for expensive cooling.
Sounds too good to be true? Yet this is exactly what a new experimental method developed by physicists at the University of Konstanz, led by Davide Bossini, makes possible. By coherently exciting magnon pairs using laser pulses, the research team has achieved astonishing effects with great potential not only for use in information technology, but potentially also for future quantum research. The surprising process was described in June 2025 in the journal Science Advances.
Technology based on magnons
But wait, let's take two steps back: What is the point of all that? It is all about technology, of course, not about magic. We live in a time in which artificial intelligence and the "Internet of Things" generate huge amounts of data. It is already apparent today that the current schemes of our information technology will soon no longer be able to cope with these volumes of data. A bottleneck threatens that will slow down technological advances.
As a solution to this problem, researchers have been proposing for some time to use electron spins as information carriers, or, more precisely, entire spin waves of sometimes hundreds of trillions of spins that oscillate together. Such collective spin excitations are called magnons and behave like a wave. With the help of lasers, they can be influenced and thus "controlled". This could enable information transmission and storage in the terahertz range in the future.
Of course, there is a catch: One limitation, for example, is that we have so far only been able to excite magnons in the state of their lowest frequencies using light. As a result, the process falls short of its potential. For the technological exploitation of magnons, being able to influence their frequency, amplitude and lifetime would be a decisive pre-requisite. The Konstanz research team led by Davide Bossini has now found a promising way to do just that. Surprisingly, the control is achieved by the direct optical excitation of magnon pairs, which are the highest frequency magnetic resonances in the material.
A huge surprise
"The result was a huge surprise for us. No theory has ever predicted it", says Davide Bossini. Not only does the process work – it also has spectacular effects. By driving high-frequency magnon pairs via laser pulses, the physicists succeeded in changing the frequencies and amplitudes of other magnons – and thus the magnetic properties of the material – in a non-thermal way. "Every solid has its own set of frequencies: electronic transitions, lattice vibrations, magnetic excitations. Every material resonates in its own way", explains Bossini. It is precisely this set of frequencies that can be influenced through the new process. "It changes the nature of the material, the 'magnetic DNA of the material', so to speak, its 'fingerprint'. It has practically become a different material with new properties for the time being", says Bossini.
"The effects are not caused by laser excitation. The cause is light, not temperature", confirms Bossini: "We can change the frequencies and properties of the material in a non-thermal way". The advantages are obvious: The method could be used for future data storage and for fast data transmission at terahertz rates without the systems being slowed down by the pileup of heat.
No spectacular high-tech materials or rare earths are required as the basis for the process, but rather naturally grown crystals – namely the iron ore haematite. "Haematite is widespread. Centuries ago, it was already used for compasses in seafaring," explains Bossini. It is perfectly possible that haematite will now also be used for quantum research in the future. The results of the Konstanz team suggest that, using the new method, researchers will be able to produce light-induced Bose-Einstein condensates of high-energy magnons at room temperature. This would pave the way to researching quantum effects without the need for extensive cooling. Sounds like magic, but it is just technology and cutting-edge research.
The project was carried out in the context of the Collaborative Research Centre SFB 1432 "Fluctuations and Nonlinearities in Classical and Quantum Matter beyond Equilibrium".
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