Towards electrical spin injection into LaAlO ₃ –SrTiO ₃

Abstract

Future spintronics devices will be built from elemental blocks allowing the electrical injection, propagation, manipulation and detection of spin-based information. Owing to their remarkable multi-functional and strongly correlated character, oxide materials already provide such building blocks for charge-based devices such as ferroelectric fieldeffect transistors (FETs), as well as for spin-based two-terminal devices such as magnetic tunnel junctions, with giant responses in both cases. Until now, the lack of suitable channel materials and the uncertainty of spin-injection conditions in these compounds had however prevented the exploration of similar giant responses in oxide-based lateral spin transport structures. In this paper, we discuss the potential of oxide-based spin FETs and report magnetotransport data that suggest electrical spin injection into the LaAlO 3 -SrTiO 3 interface system. In a local, three-terminal measurement scheme, we analyse the voltage variation associated with the precession of the injected spin accumulation driven by perpendicular or longitudinal magnetic fields (Hanle and 'inverted' Hanle effects). The spin accumulation signal appears to be much larger than expected, probably owing to amplification effects by resonant tunnelling through localized states in the LaAlO 3 . We give perspectives on how to achieve direct spin injection with increased detection efficiency, as well on the implementation of efficient top gating schemes for spin manipulation.

Highly efficient and tunable spin-to-charge conversion through Rashba coupling at oxide interfaces

“…This can be interpreted in terms of a crossover between the occupancy of one to several bands with different orbital characters and different spin-orbit textures. Our results suggest that oxide interfaces have a strong potential for spintronics 36 , both for the generation or detection of spincurrents through direct 16 The substrate-to-target distance was 63 mm. After LAO growth, the samples were then annealed for 30 min in about 400 mbar of oxygen at 500⁰C.…”

Physics of SrTiO3-based heterostructures and nanostructures: a review

“…Many of the experiments performed so far were inspired by experiments first performed with semiconductors like silicon and GaAs. [499][500][501][502][503][504][505]; spin-charge conversion by spin pumping followed inverse Edelstein effect (IEE) [478,506].…”

Multi-band theory of superconductivity at the LaAlO$_3$/SrTiO$_3$ interface

“…The gate-tunable Rashba SOI makes the interface q2DEG a potential candidate for spintronic applications 59 as well as a playground for the search of non-trivial topological excitation such as the Majorana fermions 6 or the Skyrmions 2(a), (e), the pairing amplitudes ∆ b and ∆ c decreases slowly with increasing both Rashba SOI strength γ and atomic SOI strength ∆ so because the SOI enhances precession of electrons leading to slow reduction of the electron pairing. It is interesting to note that the superconductivity in the singlet interband channel and the triplet intra-band and inter-band channels is induced by the SOI when the pairing amplitudes ∆ b or ∆ c is finite as shown in FIG.…”