In a new study published in Physical Review Letters, physicists at EPFL’s Institute of Physics have used scanning tunneling microscopy to demonstrate the stability of a magnet consisting of a single atom of holmium, an element they have been working with for years.

The scientists exposed the atom to extreme conditions that normally de-magnetize single-atom magnets, such as temperature and high magnetic fields, all of which would pose risks to future storage devices. Using a scanning tunneling microscope, the scientists found that the holmium atoms could retain their magnetization in a magnetic field exceeding 8 Tesla. The authors describe this as “record-breaking coercivity”, a term that describes the ability of a magnet to withstand an external magnetic field without becoming demagnetized.

Next, the researchers exposed a series of Holmium single-atom magnets to temperatures of up to 45 Kelvin. The Holmium single-atom magnets remained stable up to a temperature of 35K. Only at around 45K, the magnets began to spontaneously align themselves to the applied magnetic field. This showed that they can withstand relatively high temperature perturbations and might point to the way forward for running singleatom magnets at more commercially viable temperatures.

“We have demonstrated that the smallest bits can indeed be extremely stable, but next we need to learn how to write information to those bits more effectively to overcome the magnetic ‘trilemma’ of magnetic recording: stability, writability, and signal-to-noise ratio,” says EPFL’s Fabian Natterer who is the paper’s first author.

Source: École Polytechnique Fédérale de
Lausanne (EPFL)

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