The amount of information produced by modern society has grown massively in the last years, attracting increasing attention to information storage technology, because of the constant need for more powerful and efficient devices. The state-of-the-art technology includes Hard Disk Drives, Solid State Drives, and flash memories, which are based on the detection and movement of electron charges.
However, several limitations, among which the speed of writing and reading data from an HDD and the durability of SSD, have slowed down the continuous improvement of these devices, so that reducing their size and power consumption has become a serious technological issue. For this reason, it has become crucial to search for new prototypes for data storage devices.
Skyrmions, magnetic knot-like quasiparticles, have been widely proposed as the basis for new concepts in non-volatile information storage. Their main attraction lies in the fact that they can be moved using spin-torques at room temperature in thin film multilayers, with the expectation that the current densities needed can eventually be as low as the 106-107 A/m2 observed in cryogenic measurements on single crystal materials, which will permit very low energy manipulation of information. Furthermore, the non-trivial topology of a skyrmion leads to an improved stability against external perturbations. The topology of the spin texture is characterised by the skyrmion winding number S, which takes integer values, and counts the number of skyrmions in the sample.