Excitation and control of spin waves in ferromagnetic structures by fs-laser pulses

• Applicant: Professor Dr. Ilya Akimov
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 429918632

Spin waves or magnons – the elementary excitations of magnetic moments localized periodically in a crystal lattice – are considered to be promising for high speed information processing and its transport in electronic circuits. The generation of spin waves by ultrashort laser pulses provides several important advances with respect to conventional approaches using microwaves. In particular, a focused laser spot works as point source of spin waves and allows directional control of their propagation as well as switching between different types of spin waves. The project is aimed to investigate and develop optical methods for efficient and tunable spin wave generation in magnetic dielectric structures, where the inverse Faraday effect can be efficiently exploited for non-thermal control of magnetization within the laser excitation spot in combination with small Gilbert damping. Our main focus will be on the optical control of spin wave properties such as amplitude, frequency spectrum and directionality, which will be implemented by applying a pulse sequence with high repetition rate of ultimately up to 10 GHz, studying spatially confined magnetic structures, and spatial shaping of the optical field in the excitation laser spot. The decay and propagation of the spin waves will be directly resolved in time by transient pump-probe Faraday rotation measurements with micrometer spatial resolution. The obtained results will significantly contribute to the development of optical spin wave injection in magnetic dielectric structures and initiate novel photonic and optoelectronic circuits.

• DFG Programme: Research Grants
• International Connection: Russia
• Partner Organisation: Russian Foundation for Basic Research, until 3/2022
• Cooperation Partner: Privatdozent Dr. Vladimir Belotelov, until 3/2022