Voltage-tunable giant nonvolatile multiple-state resistance in sliding-interlayer ferroelectric <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>h</mml:mi><mml:mtext>−</mml:mtext><mml:mi>BN</mml:mi></mml:math> van der Waals multiferroic tunnel junction
Xinlong Dong, Xuemin Shen, Xiaowen Sun, Yuhao Bai, Zhi Yan, Xiaohong Xu
Abstract
Multiferroic tunnel junctions (MFTJs) based on two-dimensional van der Waals heterostructures with sharp and clean interfaces at the atomic scale are crucial for applications in nanoscale multiresistive logic memory devices. The recently discovered sliding ferroelectricity in 2D van der Waals materials has opened new avenues for ferroelectric-based devices. Here, we theoretically investigate the spin-dependent electronic transport properties of ${\mathrm{Fe}}_{3}\mathrm{Ge}{\mathrm{Te}}_{2}/\mathrm{graphene}/\mathrm{bilayer}\text{\ensuremath{-}}h\text{\ensuremath{-}}\mathrm{BN}/\mathrm{graphene}/\mathrm{Cr}{\mathrm{I}}_{3}$ (FGT/Gr-BBN-Gr/CrI) all-vdW MFTJs by employing the nonequilibrium Green's function combined with density functional theory. We demonstrate that such FGT/Gr-BBN-Gr/CrI MFTJs exhibit four nonvolatile resistance states associated with different staking orders of sliding ferroelectric BBN and magnetization alignment of ferromagnetic free layer $\mathrm{Cr}{\mathrm{I}}_{3}$, with a maximum tunnel magnetoresistance (electroresistance) ratio, i.e., TMR (TER) up to $\ensuremath{\sim}3.36\ifmmode\times\else\texttimes\fi{}{10}^{4}%(\ensuremath{\sim}6.68\ifmmode\times\else\texttimes\fi{}{10}^{3}%)$ at a specific bias voltage. Furthermore, the perfect spin filtering and remarkable negative differential resistance effects are evident in our MFTJs. We further discover that the TMR, TER, and spin-polarization ratio under an equilibrium state can be enhanced by the application of in-plane biaxial strain. This paper highlights the significant potential of sliding ferroelectric BBN-based MFTJs in nonvolatile memories, showcasing their giant tunneling resistance ratio, multiple resistance states, and excellent spin-polarized transport properties.