The breakthrough potentially enables electromagnetic tuning of magnetic information.
Data downloads onto mobile devices are set to become much faster with a new way of magnetic interaction discovered by researchers from the National University of Singapore (NUS). The researchers simply added a special insulator that made electrons “twirl” their neighbouring “dance partners” to transfer magnetic information over a longer range between two thin layers of magnetic materials. This novel technique enables transfer of magnetic information from one magnetic layer to another, synonymous to the encoding and transmission of data.
The findings were recently published online in the journal Nature Communications.
The data that users download from the Cloud onto their mobile devices, is actually stored in minute magnetic dots written in layers that are only a few nanometers thick and cover the surface of millions of spinning hard disks. These disks are stacked by the thousands in server farms worldwide.
“A bottleneck that stifles the progress of the big data revolution is the demand for faster data transmission rates. The recent discovery by our team paves the way for the development of devices that operate in the terahertz frequency range, which makes encoding and transmission of data many times faster,” explained Assistant Professor Ariando, co-leader of the research team.
When two magnetic layers (only ten to 100 atoms thick) are stacked close to each other, they couple together to exchange electrons with each other. The electrons carry across their spin, and the directions of magnetisation of the two layers are aligned; the electron has a magnetic field due to its spin. This coupling breaks if the two magnetic layers are separated by an insulating spacer that is more than a few atoms thick. The insulator is almost impenetrable for the free electrons.
As magnetic interactions are normally mediated by short-range exchange or weak dipole fields, the research team, which is co-led by Professor T Venky Venkatesan, Director of NUS Nanoscience and Nanotechnology Institute, sought to propagate the magnetic interaction over longer distances. They found that the use of polar oxide insulator extends the range of the magnetic coupling from about one nanometer to ten, and its strength varies up and down with spacer thickness. This discovery is startling as no electrons could ever make their way across such an impenetrable layer. In addition, the range achieved would previously have required a metallic system to transmit the electrons across the magnetic layers.
To explain this phenomenon, Professor Michael Coey of Trinity College Dublin, a visiting faculty at NUSNNI, came up with a suggestion: “Instead of spin magnetism being carried across directly by messenger electrons, it is the orbital magnetism that is passed along from atom to the next across the insulator. The atomic electrons are engaged in a dance, each twirling their partners on the neighbouring atoms until the orbital motion reaches the other side.” Spectroscopic measurements performed on the new magnetic effect proved Prof Coey’s supposition to be true.
Written by Uma Gupta, Contributing Author for Technology.Org