Researchers from Nankai University, South China Normal University and additional institutes have introduced a new approach to precisely and rapidly switch the helicity of magnetic vortices.
Their novel method involves the use of extremely short laser pulses and a magnetic field applied perpendicular to the surface of a nano-engineered material. As part of their study, the researchers first engineered tiny magnetic vortices in a magnetic material made up of 80% of nickel (Ni) and 20% iron (Fe). This magnetic alloy is promising for the development of spintronics as it possesses advantageous magnetic properties.
"We report an experimental realization of coherent helicity toggle switching in nanoscale magnetic vortices occurring on timescales of several hundred picoseconds," wrote Can Liu, Zefang Li and their colleagues in their paper.
"This switching behavior is driven by femtosecond laser pulse excitation under an out-of-plane magnetic field. The mechanism is governed by ultrafast photothermal demagnetization and coherent spin precession in the subsequent remagnetization process, during which the intrinsic topology and symmetry of the vortex are preserved."
The team essentially illuminated the nano-engineered magnetic vortices with extremely short laser pulses, heating them up briefly. As they did this, they also applied a perpendicular magnetic field.
In both computer simulations and experiments, this process was found to successfully switch the magnetic rotation (i.e., helicity) of vortices. The team carefully adjusted the strength of the laser and of the applied magnetic field, to control the switching of the magnetic vortices.
"Crucially, the helicity switching dynamics can be tuned precisely using the laser fluence and magnetic field strength, enabling deterministic to stochastic control over the two energy-degenerate helicity states," wrote the authors. "This control was reproduced in micromagnetic simulations when the parameters were optimized within a physically reasonable range."
The initial results gathered by the team highlight the potential of their approach for the ultrafast switching of helicity in magnetic vortices while preserving their structure. In the future, similar strategies could be tested on a wider range of nano-engineered magnetic materials with suitable properties.
This recent study could soon open new possibilities for the development of various highly efficient spintronics, including sophisticated data storage and neuromorphic computing devices.
In particular, the switching of magnetic vortex helicity could be used to create spintronic systems that better mirror the structure of the human brain, as well as multi-state memories that can represent stored information using more than two values (i.e., not just "0" and "1").