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Controlling and detecting spin currents using ferroelectricity

​Researchers from the CEA-Irig and the "Unité mixte de physique" CNRS-Thales have proposed a new spintronic approach based on ferroelectricity. For the first time, this approach allows spin currents to be manipulated using non-magnetic interfaces controlled by electric fields. The result: the electrical consumption of non-volatile spintronic devices can potentially be reduced by a factor of one thousand!
Published on 22 April 2020

Now that it has revolutionized digital storage with magnetic hard disks, spintronics could play an important role in the emergence of new processors beyond our present-day silicon-based technology.

Spintronics is based on a quantum property of electrons known as spin, which is at the origin of the magnetism of materials. Thus, it uses "spin currents" in addition to the charge currents of electronics. The manipulation of these exotic currents is non-volatile thanks to ferromagnetism, but requires the application of a magnetic field or a strong electric current, both of which are costly in energy.

In their work, the researchers conventionally produce a spin current in a ferromagnetic layer (here an alloy of nickel and iron) and then inject it into an interface layer where it is converted into a charge current. To change the sign of the charge current produced, it is usually necessary to reverse the magnetization of the ferromagnetic material by applying a magnetic field or a strong current to it.

Their innovation consists in introducing a ferroelectric material to perform this function. Specifically, the scientists conferred a ferroelectric character to an interface between two oxides (SrTiO3 and Al2O3) by applying a strong electric field to it. This allowed them to obtain for the first time a non-volatile bipolar electrical control of the spin/charge interconversion. They thus created a spintronic device in which the non-volatility is no longer provided by ferromagnetism but from ferroelectricity. The power generated could be used to power the next component in an integrated architecture.

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