Annika Johansson
The Edelstein effect, also known as inverse spin-galvanic effect, is a magnetoelectric phenomenon providing charge-current-to-spin conversion in systems with broken inversion symmetry. In pristine nonmagnetic materials, a finite macroscopic spin polarization can be induced purely electrically by the application of an electric field [1,2]. Originally, the Edelstein effect has been discussed for two-dimensional Rashba systems at surfaces or interfaces. Whereas for isotropic Rashba systems a large spin-orbit splitting is crucial for efficient charge-to-spin conversion, current research aims at finding novel materials beyond conventional Rashba systems providing a large direct or inverse Edelstein effect, for example three-dimensional topological insulators and oxide interfaces.
In this talk the Edelstein effect in Rashba systems and topological materials is discussed within the semiclassical Boltzmann transport theory [3,4]. Here, one focus is on finding materials in which a large Edelstein effect can be realized. Considering geometrical and topological properties, Weyl semimetals are identified as candidates for a highly efficient charge-to-spin conversion [4].
Further, SrTiO_3-based two-dimensional electron gases (2DEGs) have been found to provide a large inverse Edelstein effect [5], in particular the 2DEG emerging at the interface between SrTiO_3 and AlO [6]. The application of a gate voltage leads to a strong variation and even sign changes of the spin-to-charge conversion efficiency. This unconventional gate dependence is explained by a band-resolved analysis of the Edelstein signal. The experimentally observed spin-to-charge conversion is related to the band structure as well as the topological character and the spin texture of the 2DEG [6]. In addition the orbital Edelstein effect, originating from the orbital moments, is analyzed, which can exceed the conventionally discussed spin Edelstein effect by one order of magnitude.
[2] V. M. Edelstein, Solid State Commun. 73, 233 (1990)
[3] A. Johansson et al., Phys. Rev.B 93, 195440 (2016)
[4] A. Johansson et al., Phys. Rev.B 97, 085417 (2018)
[5] E. Lesne et al., Nat. Mater. 15, 1261 (2016)
[6] D. Vaz et al., Nat. Mater. 18, 1187 (2019)