Spin-orbit torque-mediated spin-wave excitation as an alternative paradigm for femtomagnetism

摘要: Laser-induced femtosecond demagnetization, femtomagnetism, offers a potential route to develop faster magnetic storage devices. It is generally believed that the traditional spin-wave theory, which developed for thermally driven slow can not explain this rapid demagnetization by design. Here we show once augmented laser-induced spin-orbit torque, provides highly efficient paradigm capturing low-energy excitation absent in existing mechanisms. Our different from ones, but does exclude them. Microscopically, find optical torque generates massive spin waves across several hundred lattice sites, collapsing long-range spin-spin correlation within 20 fs. finding only new experiments, also establishes an alternative femtomagnetism. expected have far-reaching impacts on future research.