Elastic and Inelastic Spin Transport in SrTiO3‐based Magnetic Heterostructure

Abstract

AbstractWith recent developments in the field of spin‐orbitronics, two‐dimensional electron gases (2DEGs) with Rashba‐type spin‐orbit coupling have emerged as an important component of spin‐based devices. One of the promising platforms is the 2DEG in SrTiO3‐based structures, which has been the fundamental building block of oxide electronics. The 2DEG formed due to the redox reactions at metal/SrTiO3 interfaces has been incorporated into magnetic heterostructures, demonstrating efficient spin‐to‐charge conversion through the inverse Edelstein effect due to the sizable Rashba spin‐orbit coupling. However, evidence for the charge‐to‐spin conversion, a technologically more important process, has been lacking, and furthermore, the spin transport mechanism in the magnetic heterostructure has been unclear. Here, the charge‐to‐spin conversion induced by the direct Edelstein effect in the 2DEG at an Al/SrTiO3 interface is demonstrated. The effective charge‐to‐spin conversion efficiency of the 2DEG exceeds 10% at room temperature, which is comparable to that of the archetypal spin‐to‐charge converter, Pt. The high effective charge‐to‐spin conversion efficiency is found to be suppressed by decreasing temperature, demonstrating a crossover of the dominant spin transport mechanism from the inelastic tunneling to elastic tunneling induced by decreasing temperature. These findings will provide a clue to unlock the full potential of oxide‐based spin‐orbitronic devices.