Creating magnetic clouds in graphene and switching them on and off

Could lead to transistor-like graphene devices
June 14, 2013

Controlling magnetic clouds in graphene (credit: The University of Manchester)

A University of Manchester team led by Dr. Irina Grigorieva has discovered how to create elementary magnetic moments in graphene and then switch them on and off, opening a new avenue towards electronics with very low energy consumption..

This is the first time magnetism itself has been toggled, rather than the magnetization direction being reversed.

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 due to the latest discovery.

Graphene is a chicken-wire-like material made of carbon atoms. It is possible to remove some of these atoms, which results in microscopic 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.

Transistor-like graphene devices

Grigorieva and her team have shown that the magnetic clouds can be controllably dissipated and then condensed back. “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.”

Professor Antonio Castro Neto, Director of the Graphene Research Centre in Singapore and co-author of the report, said: “This work opens the doors for new magnetic devices that are atomically thin and can be easily controlled externally with the application of ordinary electric fields. These new devices can be incorporate in electronic circuits in order to create functionalities for control of magnetism and charge that did not exist before. They unify magnetic memories with electric circuits. It is a true breakthrough.”

Nobel Laureate and co-author of the paper Professor Andre Geim added: “I wonder how many more surprises graphene keeps in store. This one has come out of the blue. We have to wait and see for a few years but the switchable magnetism may lead to an impact exceeding most optimistic expectations.”