For decades, scientists thought they understood nanomagnets powering hard drives and memory devices, but one important detail had remained an untested assumption until now.
Researchers at Tohoku University have successfully measured a fundamental property known as ‘attempt time’ in nanomagnets. This is the first time this value has been directly observed in an experiment, ending nearly 70 years of uncertainty.
The findings, published in Communications Materials on April 21, 2026, reveal that nanomagnets behave differently than scientists long believed. The discovery could reshape how engineers design future data storage and computing systems.
Magnets usually keep a steady direction. A compass, for example, points north because of this stability. But under certain conditions, like strong heat or magnetic fields, this direction can change. When that happens in digital storage systems, it can lead to data loss.
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Inside devices like hard disk drives, each piece of information is stored in a tiny magnetic unit. These nanomagnets have two stable states, similar to ‘on’ and ‘off.’ The system depends on these states staying fixed. If they flip unexpectedly, the stored data is lost.
This switching behavior can be explained using an energy landscape. Imagine a ball sitting in one of two valleys separated by a hill. The ball represents the magnet’s direction. Normally, it stays in one valley. But with enough energy, such as heat, it can jump over the hill into the other valley, flipping its state.
Scientists use the Arrhenius law to describe how often this happens. According to this model, the magnet repeatedly tries to cross the energy barrier. The time between these attempts is called the ‘attempt time’ and denoted by τ₀.
For nearly seven decades, researchers assumed this attempt time was about one nanosecond. However, no one had ever measured it directly. It remained a theoretical value used in models and calculations.
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The team at Tohoku University set out to change that. They built tiny nanomagnet devices and studied them in detail. Using scanning electron microscopy, they confirmed the magnets’ structure and size. Each device measured only about 50 nanometers across.
They then observed how these nanomagnets switched between two opposite magnetic states at room temperature. The switching produced a signal known as random telegraph noise. This signal showed clear jumps between two voltage levels, reflecting the magnet flipping back and forth due to thermal energy.
To analyze this behavior, the researchers developed a new method. Instead of changing temperature, they adjusted the energy barrier by altering the size of the nanomagnets and applying magnetic fields. This allowed them to test the Arrhenius law under stable conditions.
Their results challenged long-held beliefs. The measured attempt time ranged from 4 to 11 nanoseconds, more than 10 times the accepted value.
Associate Professor Shun Kanai explained the significance of the finding. He said that scientists had relied on this parameter for decades without direct evidence. He added that their experiments now show that nanomagnets attempt to switch much more slowly than previously thought.
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The study also uncovered a possible reason behind this delay. The researchers suggest that internal processes within the magnet, known as spin waves, play a role. These are collective movements of electron spins that can influence how energy spreads through the material. They appear to slow down the switching attempts.
This new understanding has practical importance. As storage devices become smaller, their magnetic components shrink as well. Smaller magnets have lower energy barriers, making them more vulnerable to unwanted switching. Knowing the true attempt time helps engineers better predict and control this risk.
The findings could improve the design of hard drives and advanced memory technologies, such as magnetoresistive random-access memory. They may also support emerging systems such as spintronic probabilistic computing devices, which intentionally use random switching as part of their function.
By finally measuring a value that was long taken for granted, the study brings clarity to a key aspect of magnet behavior. It shows that even well-established theories can yield surprises when closely tested.
This work not only fills a long-standing gap in physics but also offers a stronger foundation for the technologies that depend on these tiny yet powerful magnets.
