An international team of scientists has made a breakthrough in the magnetic manipulation of nanoparticles that could lead to a big boost for small scale digital storage in portable devices.

The research, led by scientists from the Universitat Autònoma de Barcelona and the Institut Catala de Nanociencia i Nanotecnologia, centers around the ability to produce what is known as antiferromagnetic coupling (AFM) in particles as small as 10 nanometres.

AFM is an magnetic phenomenon critical to digital data reading and storage systems such as hard drives and MRAM memory. It involves the juxtapositioning of magnetic polarity in the layers of a structure or particle. This opposing polarity is used to store data as 1s and 0s. Magnetic nanoparticles promise to underpin advances in everything from cleaning up oil spills to improving cancer detection. When it comes to push the boundaries of nano-scale digital storage, a major hurdle facing researchers has been controlling the magnetic orientation of core/shell nanoparticles, which are formed of a core of one metal and an outer coating or shell of another metal.

The researchers found that they could control the magnetic properties of certain layered nanoparticles by adjusting temperature and magnetic fields around them. This was realized using iron-oxide and manganese-oxide layers in hard-soft shell nanoparticles. These bi-magnetic layered nanoparticles produced a magnetic relationship known as positive exchange bias that, in a world first, were able to be manipulated without having to change their structure.

At this stage there is no clear indication of exactly what storage capacity gains can be expected from the application of this technology or when it might reach the marketplace, but the researchers believe their observations will lead to advances in several areas.

“We've been able to reproduce a magnetic behavior not previously observed in nanoparticles, and this paves the way for miniaturization up to limits which seemed impossible for magnetic storage and other more sophisticated applications such as spin filters, magnetic codifiers and multi-level recording”, said Josep Nogués, ICREA research professor.

The research has been published in Nature Communications.

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