Ferroelectric control of the conversion between spin and charge currents

While spintronics has traditionally relied on ferromagnetic metals as spin generators and detectors, efficient spin-charge interconversion enabled by spin-orbit coupling in non-magnetic systems has drawn considerable interest in recent years in a new field called spinorbitronics. We report a new approach to generate and detect spin currents by exploiting the interplay between spin-orbit effects and ferroelectricity, in two classes of materials: two-Dimensional Electron Gases (2DEGS) appearing at oxides surfaces or interfaces [1], and ferroelectric Rashba semiconductors [2].

Our results demonstrate that the spin-to-charge conversion, due to the spin-orbit coupling, can be controlled in sign in a remanent way, through the ferroelectric polarization. Such a control can lead to the emergence of a ferroelectric spintronics, which could result in a reduction of the power consumption of non-volatile spintronic devices by a factor of one thousand. It also provides a way for a non-destructive readout of ferroelectric states.

This provides new opportunities for creating spin-based devices, such as the MESO transistor proposed recently by Intel [3], which relies on the writing of a magnetic information through magnetoelectric coupling, and of its reading by spin-charge conversion. Indeed, by controlling directly the sign of the interconversion by a ferroelectric state, it is possible to merge in a single device its writing and reading blocks, and the need for reversing a magnetic state.

In this presentation we will present the basic principle of spin charge current interconversions in Spintronics and then how to control this spin-to-charge conversion, report our results obtained on SrTiO₃ 2D gases and on GeTe, and discuss the perspective of this work.