Optical probe deciphers data-storing potential of thin film
doi:10.1038/nindia.2019.63 Published online 20 May 2019
Physicists have used laser beams to gain new insights into the generation and transport of spin currents in a bilayer thin film made up of a ferromagnet and a non-magnet1. These insights are potentially useful for creating memory and logic devices using such films.
Particles such as electrons have spin, a property that generates spin current. Such currents are made up of the flow of spins, shunning the need of charge flow. However, there is no simple and non-invasive method to study the transport of spin current in different thin films.
To devise a simple and efficient method, scientists from the S. N. Bose National Centre for Basic Sciences in Kolkata, India, split extremely short pulses of laser beams into two parts: pump and probe beams. They used the pump beam to induce spin current in the ferromagnetic layer of the bilayer film.
Using the probe beam, they then tracked the transport of spin current from the ferromagnetic layer into the non-magnetic layer in the film across an interface between the magnetic and non-magnetic layers.
The resesearchers, led by Anjan Barman, measured interfacial spin transparency, which is a measure of the fraction of pure spin current that is transported into the nonmagnetic layer. They found that half of the spin current generated in the ferromagnetic layer was transported into the non-magnetic layer.
This determines the efficiency of spin current transport in spin current-based devices, such as magnetic storage, memory and logic devices, says Barman.
1. Panda, S. N. et al. All-optical detection of interfacial spin transparency from spin pumping in β-Ta/CoFeB thin films. Sci. Adv. 4, eaav7200 (2019)