Creation and low-current-induced drive of skyrmion molecular -Towards novel power-saving and high-density magnetic memory

Magnetic memory devices that use the electron spin as magnetic information have attracted attention as next-generation devices with the high reading/writing speed and non-volatility. The skyrmion, an electron spin vortex, can be driven with lower current density than that for driving the conventional ferromagnetic domain walls. It is because that skyrmion can avoid the pinning sites (such as crystal defects) when it moves under electric current, different from the magnetic domain walls in ferromagnets. One skyrmion with topological charge of 1 acts as one information bit.

The research group has succeeded in creating the skyrmion molecular with topological charge of 2 in the (001)-plane plate of bilayered manganite La _2-2xSr _1+2xMn ₂O ₇ ( x = 0.315) for the first time. Such a skyrmion molecular has been driven successfully with three orders of magnitude lower current density (<10 ⁸ Am ^-2) than that for the conventional ferromagnetic domain walls. Such findings will bring about great development in designing novel magnetic memory devices with high-density and low power consumption with use of skyrmions.The main portion of the research result was achieved in the “Quantum Science on Strong Correlation” project (Core Researcher: Yoshinori Tokura) of the FIRST program. The research result was obtained by Prof. Yoshinori Tokura, at the University of Tokyo in collaboration with RIKEN-CEMS (Director: Yoshinori Tokura) and Advanced Key Technologies Division (Division Director: Daisuke Fujita) at NIMS.