Thesis title: Spin‐charge conversion phenomena in two-dimensional electron gases at oxide interfaces
After finishing my MSc in Nanoscience at University of Copenhagen I have joined DTU Energy as PhD in the end of 2021 where I will be studying spin-charge current interconversion in oxide interfaces under the supervision of Felix Trier, Denis V. Christensen and Thomas Sand Jespersen.
In this project I will try to develop a platform for a novel transistor based on electron spin rather than charge. Such a transistor is predicted to consume a factor 10-30 less energy and improve the logic density by a factor 5 compared to conventional CMOS transistors.[1] However, both for the sake of measurement and potential implementation in modern technologies, the interconversion between spin and charge current needs to be optimized. Thus, a device capable of reading a charge-current-based input, convert it to a spin-current-value, perform its transistor-function on the spin current and convert it back into readable charge current is the long-term-goal of the project, with my part being the development of the spin-charge interconversion platform.
Image 2 display a phenomenon where a spin current, Js, of spin polarization σ is induced into an oxide 2DEG from a top layer of a ferromagnetic material. A 2DEG is an interface between two insulating bulk materials, that becomes conducting. As a result of this spin current, a charge current arises in the 2DEG, perpendicular to the spin current and polarization. This phenomenon is called the Inverse Rashba Edelstein Effect, or just the Inverse Edelstein effect (IEE). The conversion efficiency of IEE is proportional to the charge carrier mobility and the spin-orbit coupling. This proportionality makes the phenomenon promising in oxide 2DEGs, because the charge carrier mobility is very large in specific examples of these (140,000 in the interface between γ-Al2O3/SrTiO3 [2]).
[1] S. Manipatruni et al., “Scalable energy‐efficient magnetoelectric spin–orbit logic,” Nature, vol. 565, no. 7737, pp. 35–42, 2019, doi: 10.1038/s41586‐018‐0770‐2.
[2] Chen, Y., Bovet, N., Trier, F. et al. A high-mobility two-dimensional electron gas at the spinel/perovskite interface of γ-Al2O3/SrTiO3. Nat Commun 4, 1371 (2013). https://doi.org/10.1038/ncomms2394
Start date: 01-11-21
Finish date: 31-10-24
PhD supervisors: Felix Trier & Thomas Sand Jespersen