Researchers demonstrate control of magnetic clouds in graphene
13 June 2013
Graphene can be made magnetic and its magnetism switched on and off, opening a new avenue towards electronics with very low energy consumption.
Electrons condense around 'vacancies' in the graphene stucture, creating small electronic clouds, each behaving like a microscopic magnet carrying one unit of magnetism - spin
A University of Manchester team led by Dr Irina Grigorieva shows how to create elementary magnetic moments in graphene and then switch them on and off. The researchers say this is the first time magnetism itself has been toggled, rather than the magnetization direction being reversed.
Devices, including hard disks, memory chips and sensors employ miniature magnetic components. Each micro-magnet allows a bit of information (‘0’ or ‘1’) to be stored as two magnetization directions (‘north’ and ‘south’). This area of electronics is called spintronics.
Despite huge advances, a big disappointment of spintronics has so far been its inability to deliver active devices, in which switching between the north and south directions is done in a manner similar to that used in modern transistors. This situation may dramatically change as a result of this latest discovery, say the researchers.
Graphene is a 'chicken wire' construction of carbon atoms. It is possible to remove some of these atoms creating holes called 'vacancies'. The Manchester scientists have shown that electrons condense around these holes into small electronic clouds, and each of them behaves like a microscopic magnet carrying one unit of magnetism - spin.
Dr Grigorieva and her team have shown that the magnetic clouds can be controllably dissipated and then condensed back.
She explains: “This breakthrough allows us to work towards transistor-like devices in which information is written down by switching graphene between its magnetic and non-magnetic states. These states can be read out either in the conventional manner by pushing an electric current through or, even better, by using a spin flow. Such transistors have been a holy grail of spintronics.”
Dr Rahul Nair, who led the experimental effort, comments “Previously, one could only change a direction in which a magnet is magnetized from north to south. Now we can switch on and off the magnetism entirely. Graphene already attracts interest in terms of spintronics applications, and I hope that the latest discovery will make it a frontrunner.”