Room‐Temperature Non‐Local Spin Transport in Few‐Layer Black Phosphorus Passivated with MgO

Black phosphorus (BP), a new member of 2D materials, is an ideal selection to construct spin-based devices due to its tunable direct bandgap and high carrier mobility. Assembling van der Waals heterostructures is the most popular method to create spintronic devices for 2D materials, especially for the easily oxidized BP. However, it is too complicated to be realized for fabricating large-scale integrated circuits in practical applications. To overcome this flaw, an oxide layer on BP simultaneously serving as the protection layer and barrier to fabricate a Co/MgO/BP-based non-local spin valve is employed. The non-local spin signals demonstrate the diffusion of pure spin current in the BP channel, which is the direct evidence of the spin injection from Co into BP. Combining the Hanle precession measurements with the Bloch equation fitting, the spin transport parameters of the few-layer BP can be extracted. The spin diffusion length lambda(s) and spin relaxation time tau(s) are 6.15 mu m and 241.7 ps, respectively. Therefore, the MgO layer in the non-local spin valve can simplify the fabrication of 2D material-based spintronic devices and accelerate their applications.