Frontier Research Institute for Interdisciplinary Sciences
Tohoku University

In recent years, the rapid development of the ultra-smart society has created increasing expectations for the realization of next-generation devices with high performance, particularly magnetic memory based on the principles of spintronics. Achieving such devices requires a deep understanding of the ultrafast magnetization response properties of spin materials. The speed of magnetization is typically influenced by the energy applied during magnetization operations using electric and magnetic fields.

In this study, we draw inspiration from the pump-probe (PP) technique and employ a plasmonic device to convert a pump light femtosecond laser pulse into an electromagnetic pulse, enabling manipulation of the magnetization properties of the target material. By introducing a time-delayed probe light, we can observe the ultrafast changes in magnetization properties. The primary goal of this study is to observe a unique fast magnetization response in a novel two-dimensional material, distinct from traditional bulk magnetic materials. Additionally, we aim to investigate and demonstrate the state-of-the-art Kosterlitz-Thouless transformation and Mermin-Wagner theory in two-dimensional systems.

To achieve this, we will fabricate a device by creating a stripline waveguide (SLW) and a photoswitch (PS), and then transferring the magnetic two-dimensional material to the center of the PS. Femtosecond pump light pulses will be irradiated onto the PS to excite surface plasmon polaritons (SPPs) in ultrashort electromagnetic field pulses. These SPPs will propagate along the waveguide, reaching the magnetic two-dimensional material and driving the electron spins in the material at ultrafast rates. Simultaneously, femtosecond probe light emitted from the same light source will be used to observe the dynamic magnetization response. The results of this research will not only contribute to the understanding of magnetization reversal properties in two-dimensional materials but also facilitate the development of new memory devices based on these principles in the future.