Proximity Effect-Induced Magnetoresistance Enhancement in a Fe3GeTe2/NbSe2/Fe3GeTe2 Magnetic Tunnel Junction

The coupling between van der Waals-layered magnetic and superconducting materials holds the possibility of revealing novel physical mechanisms and realizing spintronic devices with new functionalities. Here, we report on the realization and investigation of a maximum ∼17-fold magnetoresistance (MR) enhancement based on a vertical magnetic tunnel junction of Fe₃GeTe₂ (FGT)/NbSe₂/FGT near the NbSe₂ layer's superconducting critical temperature (T_C) of 6.8 K. This enhancement is attributed to the band splitting in the atomically thin NbSe₂ spacer layer induced by the magnetic proximity effect on the material interfaces. However, the band splitting is strongly suppressed by the interlayer coupling in the thick NbSe₂ layer. Correspondingly, the device with a thick NbSe₂ layer displays no MR increase near T_C but a current dependent on transport properties at extremely low temperatures. This work carefully investigates the mechanism of MR enhancement, paving an efficient way for the modulation of spintronics' properties and the achievement of spin-based integrated circuits.