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Pure spin current created in graphene

Spintronics is a new technology that exploits the spin of an electron as well as its charge to produce smaller and more efficient electronic circuits than those available today. The spin of an electron can point in an "up" or "down" direction, and this property could be used to store and process information in spintronics devices. Such circuits are smaller and more efficient than conventional electronic circuits because they rely on switching charge alone as switching spins from up to down can be done using very little energy.


Graphene is a sheet of carbon just one atom thick that could be important for spintronics because, electron spins in the material can maintain their direction for a long time.

Pure spin current

Spintronics devices would carry or manipulate information via a pure spin current, which consists of electrons with opposite spins moving in opposite directions. However, it is difficult to generate a pure spin current in graphene because the material has a very small spin-orbit interaction. Normally, it is easy to generate pure spin current in semiconductors that have strong spin-orbit interactions through the spin Hall Effect.Spin-polarized current is a charge current with an uneven distribution of electron spin directions – that is, different numbers of up spin and down spin electrons.


The method employs ferromagnetic thin films deposited on graphene and two metal electrodes, and so could be used to make nanometre-sized spintronics devices. The degree of polarization of the current can also be easily changed by changing the Fermi energy.

Ferromagnetic proximity effect

Through the ferromagnetic proximity effect, electrons with different spins have different energies when they are under, and interact with, the ferromagnetic layer deposited on graphene. This means that electrons with differently oriented spins move differently under adiabatic pumping.

Adiabatic pumping

In adiabatic pumping, a DC electrical current is generated by two AC electrical potentials in the system and does not need a DC applied voltage. Normally, DC electric current is generated by DC voltage differences. The technique is routinely used in semiconductors to generate spin currents, but never in graphene. Future applications Future applications could include graphene quantum computers because the spin current might be used to generate spin polarization in graphene quantum dots for use as quantum bits. Spin current could also be used to control, rotate and detect spins in such qubits.

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