The field of spintronics has taken a significant step forward, thanks to the efforts of researchers at RIKEN. By measuring the dynamics of tiny magnetic vortices known as skyrmions, the team has brought low-energy devices based on spintronics closer to reality. While conventional electronics rely on shunting electric charge around circuits, spintronics utilizes the spin property of electrons to create faster and more efficient devices. Hazuki Kawano-Furukawa and her colleagues at the RIKEN Center for Emergent Matter Science are pioneers in this field, exploring the potential of nanoscale magnetic whirlpools like skyrmions.
Skyrmions hold great promise for future applications in information and communication technologies, such as power-free computer memory. They can be controlled with significantly smaller currents or electric fields compared to traditional electronic devices. To better understand the characteristics of skyrmions, the researchers focused on manganese monosilicide, a helimagnet where spins in its molecular lattice align in helical patterns. However, studying the lowest energy magnetic excitations in the skyrmion states required the use of extremely sensitive equipment.
To measure the dynamics of skyrmions, the team used a state-of-the-art neutron spin echo technique. This technique fulfills both spatial and energy resolution requirements, making it the ideal choice for the experiment. The researchers conducted their experiments at the Institut-Laue-Langevin in Grenoble, France, using the IN15 neutron spin echo spectrometer. This instrument is renowned for its high performance in studying material dynamics in magnetic fields. By illuminating the sample with a beam of neutrons and measuring how the magnetic fields of the sample affect the spin and velocity of the neutrons, the researchers gained valuable insights into the behavior of skyrmions.
Through their observations, the team was able to verify theoretical predictions about the properties of skyrmions in manganese monosilicide. The string-like structures of skyrmions were found to cause an asymmetric dispersion of excitations in the molecular lattice. These excitations exhibit distinct behavior depending on whether they travel parallel or antiparallel to the cores of the skyrmion whirlpools. This confirmation of theory paves the way for further exploration and exploitation of skyrmions in spintronic devices.
Two Years of Research
The journey towards these findings was not without challenges. The team had to wait for two years to confirm their results. The initial experiment was conducted in October 2018, but additional research was required to ensure that the observed behavior was exclusive to the skyrmion phase and not the conical phase of the material’s magnetic structure. Moving forward, the researchers aim to investigate the coexistence of the conical and skyrmion phases in manganese monosilicide, further expanding our understanding of these magnetic structures and their potential applications in practical devices.
The RIKEN researchers have made significant progress in the development of low-energy spintronic devices by examining the dynamics of skyrmions. The utilization of nanoscale magnetic whirlpools holds substantial promise for future information and communication technologies. By confirming theoretical predictions and applying advanced measurement techniques, the team has deepened our understanding of skyrmions’ properties in manganese monosilicide. While the journey has been long, the findings open up new avenues for research and bring us one step closer to harnessing the power of spintronics in real-world applications.