On September 28, 2020, a team of researchers from the Quantum Center of the Moscow Institute of Physics and Technology (MIPT), Saratov State University, and Michigan Technological University demonstrated a laser pulse controlled bismuth iron garnet nanostructure. A new method of spinning waves. This technology has considerable application potential in energy-saving information transfer and spin-based quantum computing.

The film used in this study has a fine structure: a smooth lower layer with a one-dimensional grating formed on top with a period of 450 nm. This geometry can excite magnons with a very specific spin distribution, which is impossible for unmodified films.

Pulsed laser refers to the effect of cutting off the surface of a certain object, removing impurities or measuring distance by emitting light or electric waves intermittently. The intermittent time of the pulsed laser is the same, similar to the working principle of the flashlight. By turning off and on, the local heat generation is reduced, but the time for the pulsed laser to turn off and on can reach the level of picoseconds.

The laser pump pulse generates magnons by locally disrupting the spin sequence (shown in orange) in the bismuth iron garnet. Then, the detection pulse shown in blue is used to recover information about the excited magnon.

The laser pump pulse generates magnons by locally disrupting the orange spin sequence in the bismuth iron garnet. The blue probe pulse is then used to recover information about the excited magnon.

Spin refers to the inherent angular momentum of a particle, which always has a direction. In a magnetized material, the spins point in the same direction. The propagation of the spin wave is accompanied by the local destruction of this magnetic order, and the quantum of the spin wave is the magnon.

Unlike electric current, spin wave propagation does not involve the transfer of matter. The heat loss caused by the use of horse farmers instead of electrons to transmit information is much smaller. The data can be encoded in the phase or amplitude of the spin wave, and can be processed by wave interference or nonlinear effects.