Writing of electronic data to materials using ultrashort X-ray pulses is promising because it could pave the way for the future development of ultrafast and compact memory storage or ultrafast information processing technologies based on light. X-ray imaging of magnetic domain states is also extremely difficult, requiring huge, costly devices – this new application could overcome some of the challenges.
The researchers wrote their data (an ‘X’ and an ‘F’) in nickel oxide thin films with the help of two pulses from the powerful free-electron laser FLASH: one pulse triggered a change of the magnetic order on the microscopic scale; a delayed second pulse imaged the magnetic patterns and thus made them “visible”.
It’s a proof of principle,” says principal investigator Thomas Gahl from the Department of Coherent X-ray Imaging at DESY’s Center for Free-Electron Laser Science CFEL. With such light-induced all-optical memory writing methods in solid-state materials, storage devices using optical pulses instead of conventional electronic devices could operate 100 to 1000 times faster and provide access times up to a million times quicker. However, he admits, several challenges like controlling data read-out remain before it might move out of the lab. Gahl is optimistic: “A significant number of research groups worldwide already have started efforts into exploiting optical writing,” he adds. “For us at CFEL, this was not only interesting in terms of fundamental magnetic-material physics research; these insights contribute as well to understanding material processes behind optically addressed memory writing that are currently at the heart of research activity around the world as one step towards future computing applications.
