Designing novel physical states in condensed matter physics

Tailoring emergent spin phenomena in Dirac material heterostructures
Fig. 1 Gr-TI heterostructure. (A) Schematic representation of a device consisting of a Gr-TI heterostructure channel and ferromagnetic (FM) tunnel contacts for spin injection and detection in a nonlocal transport geometry. The insets show the band structures of Gr and TI, as well as the splitting in Gr bands expected in a heterostructure region. (B) SEM micrograph of the fabricated device showing the Gr-TI heterostructure channel with FM tunnel contacts of TiO2 (1 nm)/Co (60 nm) on Gr. Scale bar, 2 μm.

Dirac materials such as graphene and topological insulators (TIs) are known to have unique electronic and spintronic properties. We combine graphene with TIs in van der Waals heterostructures to demonstrate the emergence of a strong proximity-induced spin-orbit coupling in graphene.

By performing spin transport and precession measurements supported by ab initio simulations, we discover a strong tunability and suppression of the spin signal and spin lifetime due to the hybridization of graphene and TI electronic bands. The enhanced spin-orbit coupling strength is estimated to be nearly an order of magnitude higher than in pristine graphene. These findings in graphene-TI heterostructures could open interesting opportunities for exploring exotic physical phenomena and new device functionalities governed by topological proximity effects.

Heterostructures of materials with complementary electronic and topological properties have served as a foundation for designing novel physical states in condensed matter physics.

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