At the speed of (laser) light
The speed of magnetic media, such as hard discs or magnetic random access memory (MRAM), is an important factor driving technology. Although they are called storage or memory devices, the functionality of such media is deeply rooted in data access and retrieval for processing. Based on the current technology for magnetisation reversal, the speed of these spintronic devices is approaching its limit. Controlling magnetisation with light is a promising approach given the very fast pulses of ultrafast lasers, now in the terahertz (THz) range (trillions of cycles per second). However, many issues must be addressed before a true THz optomagnetic 'revolution' in magnetic recording and information processing can be achieved. In response, scientists initiated the EU-funded project 'Ultrafast all-optical magnetization reversal for magnetic recording and laser-controlled spintronics' (Ultramagnetron). Investigators first sought to develop a fundamental understanding of laser-induced magnetisation reversal in nanomagnets smaller than 300 nanometres (nm). Using this knowledge, they developed ways to control the ultrafast (less than 100 picoseconds (ps)) reversal with spatial resolution or localisation on the nano scale, better than 300 nm. They then turned to improving the speed of magnetisation reversal to less than 1 ps using ultrafast femtosecond laser control. Ultramagnetron greatly advanced the state of opto-nanomagnetism. Scientists discovered novel mechanisms for magnetisation reversal on a scale of less than 100 ps in structures of size down to 200 nm. In particular, the consortium developed novel approaches for the control of nanomagnetism on a ps timescale that previously could not even have been predicted. Industrial partners are evaluating the future of the optomagnetic technology in their product lines. Thanks to Ultramagnetron outcomes, ultrafast magnetic storage and processing devices may be just around the corner.
