Transport properties of multiferroic tunnel junctions based on sliding ferroelectric VTe<sub>2</sub>

Multiferroic tunnel junctions (MFTJs), characterized by a ferroelectric barrier encapsulated between two ferromagnetic electrodes, represent a highly promising platform for next-generation nonvolatile memory applications. The recent discovery of intrinsic ferromagnetism and ferroelectricity in van der Waals (vdW) materials further provides a compelling material foundation for constructing multifunctional MFTJs based on vdW heterostructures. In this paper, aiming at high-performance and multifunctional van der Waals multiferroic tunnel junctions (vdW-MFTJs) devices, we investigate the spin-dependent transport properties of vdW-MFTJs with a bilayer VTe<sub>2</sub> sliding ferroelectric barrier and Fe<sub>3</sub>GaTe<sub>2</sub>/Fe<sub>3</sub>GeTe<sub>2</sub> magnetic electrodes by using first-principles calculations based on density functional theory (DFT). Our results reveal that multiple non-volatile resistance states can be achieved by controlling the polarization direction of the ferroelectric barrier and the magnetization configuration of the ferromagnetic electrodes in the Fe<sub>3</sub>GaTe<sub>2</sub>/bilayer VTe<sub>2</sub>/Fe<sub>3</sub>GeTe<sub>2</sub> MFTJs. Specifically, when the double-layer ferroelectric material VTe<sub>2</sub> undergoes relative interlayer slippage, the polarization of the ferroelectric barrier switches from a left-oriented state (<i>P</i><sub>←</sub>) to a right-oriented state (<i>P</i><sub>→</sub>). Consequently, the tunneling magnetoresistance (TMR) ratio at the Fermi level increases from 7.27×10<sup>5</sup>% to 1.01×10<sup>6</sup>%. Moreover, switching the magnetization configuration of the ferromagnetic electrodes from parallel alignment (<i>M</i><sub>↑↑</sub>) to antiparallel alignment (<i>M</i><sub>↑↓</sub>) leads to an almost twofold increase in the tunneling electroresistance (TER) ratio. Furthermore, nearly 100% spin filtering efficiency is observed in all four non-volatile resistance states of the MFTJs. These findings demonstrate that the engineered Fe<sub>3</sub>GaTe<sub>2</sub>/bilayer VTe<sub>2</sub>/Fe<sub>3</sub>GeTe<sub>2</sub> MFTJs hold promising potential applications in multi-state non-volatile memory and spin filters, providing a versatile platform for developing multifunctional electronic devices.