Making the switch

An international research team, led by scientists at the London Centre for Nanotechnology (LCN) and the University of Chicago, has found a way to switch a material’s magnetic properties from ‘hard’ to ‘soft’ and back again – something which could pave the way to new control of electromagnetic devices.

The researchers tuned a magnet by subjecting it to a second magnetic field, perpendicular to the original.

Magnets can be classified by their ‘hard’ or ‘soft’ magnetic properties. Hard magnets, sometimes called ‘permanent’ magnets, have fixed or ‘pinned’ domain walls which mean the material stays magnetised for a long time. Soft magnets have moveable domain walls that can be easily flipped. These materials exhibit impermanent magnetic properties.

Prof Gabriel Aeppli, Director of the LCN and a senior member of the research team, explained the significance of the research.

'Whether a magnet is hard or soft determines what you can use it for. Typically, you would use a permanent magnet to fix a note to the door of your refrigerator because you want it to stay there for a long time. On the other hand, you might use a soft magnet in a motor or transformer because it would be better at adapting to the rapid changes in alternating current and would dissipate much less energy than a hard magnet,' he said.