NederlandsNeutrons show how laser pulses keep a magnet out of balance
Researchers at the US Oak Ridge National Laboratory pushed a magnetic material out of balance with laser pulses and looked inside it with neutrons. The unusual state lasted as long as the laser kept pulsing.
Magnets are everywhere in computers, from hard drives to memory. Physicists want to be able to control the magnetic properties of a material quickly and precisely, for example with light. But to do that, they need to see what happens inside the material while they are controlling it. That is difficult, because most measurements only show what the material looks like before or after it is controlled.
Researchers at the US Oak Ridge National Laboratory (ORNL) have now managed to do this. They used fast laser pulses to push a magnetic material out of its resting state and, at the same time, looked inside it with neutrons. Their results were published in April 2026 in the scientific journal Nature Communications. ORNL announced the work on 9 November 2026.
Ripples in a magnet
In a magnetic material, the atoms behave like tiny compass needles. These needles can move together: one needle tilts a little, then the next, like a wave moving through the crowd in a stadium. Such a ripple is called a magnon. Magnons can carry information, which makes them interesting for future electronics.
The team studied a flat magnetic material in which the needles lie in a square pattern and point in alternate directions. Neutrons, particles from the atomic nucleus without an electric charge, pass easily through such a material. On the way, a neutron can create a magnon and lose energy in the process, or absorb a magnon and gain energy. From the energy of the neutrons that come out, the researchers can read what the magnons are doing. For this they used ORNL's Spallation Neutron Source, a large facility that produces beams of neutrons.
A balance that no longer holds
In a material at rest, these two kinds of events occur in a fixed ratio that depends only on the temperature. Physicists call this 'detailed balance'. Under the laser pulses, the researchers saw extra signal on only one side: there were more magnons than there should be at that temperature. So the balance was broken.
This surplus lasted as long as the laser kept pulsing. According to the team, this is therefore not a brief warming that fades away at once, but a stable state that the laser maintains. Researcher Chengyun Hua of ORNL says that nobody has measured such a broken balance directly in a solid material before.
Hua developed the approach together with Barry Winn of ORNL and Alan Tennant of ORNL and the University of Tennessee. A researcher from the Japanese research centre J-PARC also took part. According to ORNL, the same combination of lasers and neutrons can also show what happens in other materials while they are being controlled.
What does this mean for the road to the singularity?
Faster and more energy-efficient computers need materials that can be controlled precisely. With this measuring method, researchers can now see what happens inside a magnet while light is controlling it, instead of only seeing the result afterwards. According to ORNL, better control of such magnets could one day help reduce information loss when data is transmitted, improve memory and advance quantum technology. This is fundamental research: a new measuring tool with which physicists can take the next steps towards such applications.
What is the technological singularity? Read the explanation →
