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Magnetizing graphene

Researchers of UK have discovered that graphene can be magnetized by passing a current of electrons through it.

The effect could prove useful in creating spintronic or quantum-information devices that use the spin of the electron. It makes a way to produce simple and robust spin current sources, which could have many applications. Spin currents can be used to retrieve information stored in magnetic devices. It is possible to transfer information to spatially different locations via voltage signals, which are easy to process and detect.


Graphene is a one-atom-thick material with exciting potential. Graphene can be used in many industries, from electronics to water purifiers, from displays to super-capacitors and car batteries. A peculiarity of graphene is that even a very small concentration of charge carriers will hold the magnetization. This is unlike normal substances in which opposite spins can be induced, but a large number of charge carriers are required to maintain the magnetization. If the concentration of charge carriers is decreased, most materials begin to act as insulators and the magnetization is lost. But in graphene the dominant phenomenon of magnetization occurs.

Spin currents

Researchers passed electrical current along a piece of graphene in the presence of a small magnetic field and found that spin-up and spin-down currents are produced in opposite directions, perpendicular to the direction of the electrical current and this effect magnetizes the graphene sheet. The discovery was made after studying graphene grown on an oxidized silicon wafer and crystals of hexagonal boron nitride placed between the graphene and the silicon wafer. Thus net magnetization has been created in graphene using spin currents and generating spins in graphene with no magnetic moment.

Dirac point

The effect is related to an unusual property of graphene – a Dirac or 'neutrality' point where the valence and conduction bands meet. Particles above the Dirac point and holes below the Dirac point react in opposite ways to a magnetic field. Due to imbalance, large up spins make their Fermi surface lie in the particle-like region and less down spins make their Fermi level hole-like to create a strong spin current.

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