Electrical Control and High-Bias Enhancement of Magnetoresistance in van der Waals Antiferromagnetic Spin-Filter Tunnel Field-Effect Transistor.

We report a vertical spin-filter tunnel field-effect transistor (Spin-TFET) based on the air-stable van der Waals antiferromagnet CrSBr, integrated in a graphite/hBN/graphene/CrSBr/graphene heterostructure. Electrostatic gating enables direct electrical tuning of the spin-filter tunneling magnetoresistance (MR) over a wide range, from ∼100% to ∼800%. Strikingly, the source-drain bias (VDS) amplifies spin filtering rather than suppressing it, in sharp contrast to the conventional magnetic tunnel junction, boosting the MR up to ∼2500% (25,000% in a thicker sample) at an optimal bias and sharpening the discrete MR plateaus. To elucidate the underlying mechanisms, we combine magneto-transport measurements with density functional theory calculations and a spin-polarized Wentzel-Kramers-Brillouin (WKB) tunneling model. We show that the gate electric field tunes the electrochemical potential of graphene and the spin-dependent CrSBr barriers' height of the nearby layers at the bottom graphene/CrSBr interface. The WKB model further captures, both qualitatively and quantitatively, the VDS dependence of the MR. It reveals that a high VDS regime activates a progressive tilting of the spin-dependent barrier profile across the CrSBr layer. These results establish van der Waals antiferromagnetic Spin-TFETs as a practical and electrically programmable platform for bias-amplified spin filtering, with direct prospects for multilevel spin logic and spin-selective readout.