Electrical control of spin orbit effects

Laurent VILA

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. 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], ferroelectric Rashba semiconductors [2] and at surfaces of Topological Insulators [3].
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 opens new opportunities for creating spin-based devices, such as the MESO transistor proposed recently by Intel [4], 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 the control of this spin-to-charge conversion, report our results obtained on SrTiO3 2D gases, the ferroelectric Rashba semiconductors GeTe and the gate control of the bilinear MR of the TI HgTe [3]. We will discuss the perspective of this work.

[1] P. Noel et al., Nature 580, 483–86 (2020).
[2] S. Varotto et al., Nature Electronics 4, 740 (2021).
[3] Y. Fu et al., arXiv:2111.15594 (2021).
[4] S. Manipatruni et al., Nature 565, 35–42 (2019).