Researchers from Eindhoven University of Technology (TUE) have found a fast, laser-based method for writing data to storage devices. They improve upon all-optical switching (AOS) of magnetic materials. The results show how laser pulses can accurately and quickly change spin states in magnetic materials.
According to TUE, we need new, fast and energy-efficient methods to read and write data on storage devices. Optical-based approaches have received attention over the last decade following the development of AOS for magnetic materials. However, AOS has issues with precision. The researchers developed a method to accurately write data to a cobalt-gadolinium (Co/Gd) layer with a laser pulse using a ferromagnetic material as a reference to help with the writing process.
AOS uses femtosecond laser pulses to switch the orientation of magnetic spins at the picosecond scale. Two mechanisms can be used to write data: multiple-pulse and single-pulse switching. In multiple-pulse switching, the final orientation of the spins (ie up or down) is deterministic. This mechanism requires multiple lasers, which slows the speed and efficiency of writing. Single-pulse writing would be faster but requires reading the bit before it can be overwritten, thus limits speed.
The researchers from the Physics of Nanostructures group in TUE’s Department of Applied Physics have now demonstrated a new approach that can achieve deterministic single-pulse writing in magnetic storage materials. In this deterministic single-pulse approach, the final direction of the bit only depends on the process used to set and reset the bit, making the writing process more accurate.