Spin Transport Modulation of 2D Fe 3 O 4 Nanosheets Driven by Verwey Phase Transition.

Realizing spin transport between heavy metal and two-dimensional (2D) magnetic materials at high Curie temperature (T C ) is crucial to advanced spintronic information storage technology. Here, environmentally stable 2D nonlayered Fe 3 O 4 nanosheets are successfully synthesized using a reproducible process and found that they exhibit vortex magnetic domains at room temperature. A Verwey phase transition temperature (T V ) of ≈110 K is identified for ≈3 nm thick nanosheet through Raman characterization and spin Hall device measurement of the Pt/Fe 3 O 4 bilayer. The anisotropic magnetoresistance ratio decreases near T V , while both the spin Hall magnetoresistance ratio and spin mixing conductance (G r ) increase at T V . As the temperature approaches 112 K, the anomalous Hall effect ratio tends to become zero. The maximum G r reaches ≈5 × 10 15 Ω -1 m -2 due to the clean and flat interface between Pt and 2D nanosheet. The observed spin transport behavior in Pt/Fe 3 O 4 spin Hall devices indicates that 2D Fe 3 O 4 nanosheets possess potential for high-power micro spintronic storage devices applications.