Giant tunneling magnetoresistance and electroresistance in a two-dimensional VSi2N4/In2Te3 multiferroic tunnel junction

${\mathrm{VSi}}_{2}{\mathrm{N}}_{4}$ is a newly reported magnetic semiconductor and is promising for being turned into a half metal. For this purpose, we construct a ${\mathrm{VSi}}_{2}{\mathrm{N}}_{4}$/${\mathrm{In}}_{2}{\mathrm{Te}}_{3}$ van der Waals multiferroic heterostructure based on first-principles calculations. It is found that the inversion of ferroelectric polarization of monolayer ${\mathrm{In}}_{2}{\mathrm{Te}}_{3}$ can efficiently modulate the electronic states of monolayer ${\mathrm{VSi}}_{2}{\mathrm{N}}_{4}$. A phase transition of ${\mathrm{VSi}}_{2}{\mathrm{N}}_{4}$ from semiconductor to half metal can be effectually realized, leading to distinct electronic transport properties. Next, we design a magnetic tunnel junction (MTJ) (using the ${\mathrm{VSi}}_{2}{\mathrm{N}}_{4}$ monolayer as the tunneling barrier and the multiferroic heterostructure as the electrode) and investigate its transport properties in various magnetic configurations under different polarization directions of the ferroelectric ${\mathrm{In}}_{2}{\mathrm{Te}}_{3}$ layer by combining the nonequilibrium Green's function with density functional theory. The results show that the junction exhibits half-metallic transport in the parallel magnetic configuration and near-zero transport in the antiparallel magnetic configuration, resulting in a giant tunneling magnetoresistance ratio of $\ensuremath{\sim}1\ifmmode\times\else\texttimes\fi{}{10}^{12}%$. Moreover, a $\ensuremath{\sim}1\ifmmode\times\else\texttimes\fi{}{10}^{17}%$ tunneling electroresistance ratio is achieved in the parallel magnetic configuration accompanying the polarization reversal. The findings suggest that MTJs based on the ${\mathrm{VSi}}_{2}{\mathrm{N}}_{4}$/${\mathrm{In}}_{2}{\mathrm{Te}}_{3}$ heterojunction have great potential for applications in multifunctional spintronic devices.