Diving into magnets

First-time 3D imaging of internal magnetic patterns

Magnets are found in motors, in energy production and in data storage. A deeper understanding of the basic properties of magnetic materials could therefore impact our everyday technology. A study by scientists at the Paul Scherrer Institute PSI in Switzerland, the ETH Zurich and the University of Glasgow has the potential to further this understanding.

The researchers have for the first time made visible the directions of the magnetisation inside an object thicker than ever before in 3D and down to details ten thousand times smaller than a millimetre (100 nanometres). They were able to map the three dimensional arrangement of the magnetic moments. These can be thought of as tiny magnetic compass needles inside the material that collectively define its magnetic structure. The scientists achieved their visualisation inside a gadolinium-cobalt magnet using an experimental imaging technique called hard X-ray magnetic tomography which was developed at PSI. The result revealed intriguing intertwining patterns and, within them, so-called Bloch points.

At a Bloch point, the magnetic needles abruptly change their direction. Bloch points were predicted theoretically in 1965 but have only now been observed directly with these new measurements. The researchers published their study in the renowned scientific journal Nature.

>Read More on the PSI website

Image: A vertical slice of the internal magnetic structure of a sample section. The sample is 0.005 millimetres (5 micrometres) in diameter and the section shown here is 0.0036 millimetres (3.6 micrometres) high. The internal magnetic structure is represented by arrows for a vertical slice within it. In addition, the colour of the arrows indicate whether they are pointing towards (orange) or away from the viewer (purple). (Graphics: Paul Scherrer Institute/Claire Donnelly)

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