Spectroscopy influences nanoscale electronics design
The impact of the edges of metallic thin films on their magnetic properties has been probed by scientists at the National Institute of Standards and Technology (NIST) in Gaithersburg, USA, in conjunction with IBM and MIT. These results could influence the design of nanoscale electronics.
Ferromagnetic thin films are used in microelectronic devices such as computer hard drives. As electronic components get smaller, the edges of the thin films become a larger fraction of the surface, making it more important to define their properties – a process that had not previously been carried out, says NIST.
‘Before we started this project, we didn’t even have a vocabulary to describe the magnetic properties of film edges,’ says Dr Robert McMichael of NIST.
Using a spectroscopic technique, researchers beamed microwaves of different frequencies over the edges of a 10-65nm thick nickel-iron alloy that was layered on an array of parallel nanowires on top of a silicon disk. By measuring the resultant resonances, the team could compare the magnetic behaviours of the edges to the film’s centre.
‘There is a low-field region near the edge due to demagnetisation fields that oppose the applied field,’ says McMichael. ‘Consequently, the edge’s resonances occurs at a lower frequency [than in the centre].’
This could help predict the behaviour of magnetic structures when they are scaled down to the nanoscale.