The film was taken using an X-ray microscope and shows magnetic vortices being formed in ultrafast memory cells.
“For the first time, we can observe the switching of these magnetic cells in detail.” For their investigation, the researchers chose a memory cell made of an alloy of nickel and iron, which can be magnetised in less than a billionth of a second.
Each of the memory cells has four magnetic regions, so-called domains, whose magnetic field varies either in a clockwise or anti-clockwise direction. The individual magnetic domains are triangular, with their apexes meeting in the centre of the storage cell, producing a magnetic vortex core in the centre of the cell. When the contents of the memory cell are erased by an external magnetic field, the magnetic vortex core is driven out of the cell. The external magnetic field forces the entire memory cell into a state of uniform magnetisation.
Once the field is switched off, the cell once again forms four magnetic domains with a central vortex – whose direction depends on that of the applied magnetic field; in other words, new data is written to the cell.