Magnetic sandwich between two worlds

An international research team involving Stockholm University creates a bridge between the macroscopic and quantum worlds. An international research team, including Stefano Bonetti, a researcher at Fysikum in Stockholm, and led by Helmholtz-Zentrum Dresden-Rossendorf (HZDR), has developed an effective new method for making electromagnetic waves - the waves that allow our mobile phones to communicate - interact with microscopic "spin waves", or magnetic waves.

Geometry-dependent SOT-driven magnetization dynamics
Geometry-dependent SOT-driven magnetization dynamics

The experts report in Nature Physics that their experiments, in line with the theoretical calculations presented in the same article, shed light on the basic mechanism of this previously unknown process. The results are an important step in the development of new, energy-saving magnetic computing technologies.

"The essence of the research," reports Bonetti, "is that we have been able to trigger magnetic waves in a material with a wavelength of a billionth of a metre and at very high frequencies (1000 GHz, a thousand times faster than today's processors). Theoretically, these waves can be used to transmit information in miniaturised electronic components with very high frequencies and low energy consumption.

The originality of these results is that the magnetic waves in the material were created using light with a wavelength a million times longer than the magnetic waves themselves. This is normally impossible: it would be like trying to pluck the string of a guitar with a pick that is a million times bigger than the guitar.

By creating a special "sandwich" of very thin materials, we were able to circumvent this problem, which was one of the main obstacles to this technique. There are still other problems, but this is a fundamental step forward that will allow us to create a bridge between the macroscopic world in which we live and the microscopic world of quantum physics.

More information

Coupling of terahertz light with nanometre-wavelength magnon modes via spin–orbit torque