Giant spin-to-charge conversion at an all-epitaxial single-crystal-oxide Rashba interface with a strongly correlated metal interlayer
Shingo Kaneta‐Takada, Miho Kitamura, Shoma Arai, T. Arai, Ryo Okano, Lê Đức Anh, Tatsuro Endo, Koji Horiba, Hiroshi Kumigashira, Masaki Kobayashi, Munetoshi Seki, Hitoshi Tabata, Masaaki Tanaka, Shinobu Ohya
Abstract
Abstract The two-dimensional electron gas (2DEG) formed at interfaces between SrTiO 3 (STO) and other oxide insulating layers is promising for use in efficient spin-charge conversion due to the large Rashba spin-orbit interaction (RSOI). However, these insulating layers on STO prevent the propagation of a spin current injected from an adjacent ferromagnetic layer. Moreover, the mechanism of the spin-current flow in these insulating layers is still unexplored. Here, using a strongly correlated polar- metal LaTiO 3+ δ (LTO) interlayer and the 2DEG formed at the LTO/STO interface in an all-epitaxial heterostructure, we demonstrate giant spin-to-charge current conversion efficiencies, up to ~190 nm, using spin-pumping ferromagnetic-resonance voltage measurements. This value is the highest among those reported for all materials, including spin Hall systems. Our results suggest that the strong on-site Coulomb repulsion in LTO and the giant RSOI of LTO/STO may be the key to efficient spin-charge conversion with suppressed spin-flip scattering. Our findings highlight the hidden inherent possibilities of oxide interfaces for spin-orbitronics applications.