Metal/SrTiO${}_3$ two-dimensional electron gases for spin-to-charge conversion

Abstract

SrTiO${}_3$-based two-dimensional electron gases (2DEGs) can be formed through the deposition of epitaxial oxides like LaAlO${}_3$ or of reactive metals such as Al. Such 2DEGs possess a finite Rashba spin-orbit coupling that has recently been harnessed to interconvert charge and spin currents through the direct and inverse Edelstein and spin Hall effects. Here we compare the formation and properties of 2DEGs generated in SrTiO${}_3$ by the growth of Al, Ta and Y ultrathin films by magnetron sputtering. By combining in situ and ex situ X-ray photoelectron spectroscopy (XPS) we gain insight into the reduction of the SrTiO${}_3$ and the appearance of Ti${}^{3+}$ states associated with 2DEG formation, its reoxidation by exposure to the air, and the transformation of the metal into its binary oxides. We extract the carrier densities through magnetotransport and compare them with the XPS data. Finally, working with samples covered by an extra layer of NiFe, we perform spin-pumping ferromagnetic resonance experiments and investigate spin-charge conversion as a function of gate voltage. We identify trends in the data across the different sample systems and discuss them as a function of the carrier density and the transparency of the metal oxide tunnel barrier.

References in corpus (18)

• Magnetic effects at the interface between nonmagnetic oxides
• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• Tunable Rashba spin-orbit interaction at oxide interfaces
• Highly efficient and tuneable spin-to-charge conversion through Rashba coupling at oxide interfaces
• Spin-pumping into surface states of topological insulator α-Sn, spin to charge conversion at room temperature
• Profiling the interface electron gas of LaAlO3/SrTiO3 heterostructures by hard X-ray photoelectron spectroscopy
• Instability, Intermixing and Electronic Structure at the Epitaxial LaAlO3/SrTiO3(001) Heterojunction
• Universal Fabrication of Two-Dimensional Electron Systems in Functional Oxides
• Rewritable nanoscale oxide photodetector
• Spin Pumping and Inverse Spin Hall Effect in Germanium
• Band offsets and density of Ti3+ states probed by X-ray photoemission on LaAlO3/SrTiO3 heterointerfaces and their LaAlO3 and SrTiO3 bulk precursors
• Topological states at the (001) surface of SrTiO3
• Efficient intrinsic spin-to-charge current conversion in an all-epitaxial single-crystal perovskite-oxide heterostructure of La0.67Sr0.33MnO3/LaAlO3/SrTiO3
• Tuning up or down the critical thickness in LaAlO3/SrTiO3 through in situ deposition of metal overlayers
• Two-dimensional electron system at the magnetically tunable EuO/SrTiO${}_3$ interface
• A switchable two-dimensional electron gas based on ferroelectric Ca:SrTiO${}_3$
• Controlling the electronic interface properties of AlO${}_x$/SrTiO${}_3$ heterostructures
• Negligible thermal contributions to the spin pumping signal in ferromagnetic metal-Platinum bilayers

Cited by in corpus (12)

• Electrical control of magnetism by electric field and current-induced torques
• Spin-charge interconversion in KTaO${}_3$ two-dimensional electron gases
• Spin-orbit readout using thin films of topological insulator Sb2Te3 deposited by industrial magnetron sputtering
• From low-field Sondheimer oscillations to high-field very large and linear magnetoresistance in a SrTiO${}_3$-based two-dimensional electron gas
• Controlling the electronic interface properties of AlO${}_x$/SrTiO${}_3$ heterostructures
• Spin to charge conversion at Rashba-split SrTiO${}_3$ interfaces from resonant tunneling
• A Laser-ARPES View of the 2D Electron Systems at LaAlO3/SrTiO3 and Al/SrTiO3 Interfaces
• Externally controlled and switchable 2D electron gas at the Rashba interface between ferroelectrics and heavy $d$ metals
• Achieving superconductivity in infinite-layer nickelate thin films by aluminum sputtering deposition
• Spontaneous nonreciprocal transport in a gate-tunable ferromagnetic Rashba 2-dimensional electron gas
• Controlling Spin-Mixing Conductance in KTaO${}_3$ 2DEGs by Varying Argon-Ion Irradiation Time
• Lithography-free patterning of SrTiO${}_3$-based two-dimensional electron gases using direct atomic layer processing