  Antiferromagnetic spintronics exhibits ultra-high operational speed and
stability in a magnetic field, holding promise for the realization of
next-generation ultra-high-speed magnetic storage. However, theoretical
exploration of the electronic transport properties of
antiferromagnetic-multiferroic tunnel junction (AMFTJ) devices remains largely
unexplored. Here, we design an antiferromagnet/ferroelectric
barrier/antiferromagnet van der Waals heterojunction, renamed vdW AMFTJ, using
a bilayer MnBi$_2$Te$_4$/In$_2$Se$_3$/bilayer MnBi$_2$Te$_4$ (MBT-2L/IS/MBT-2L)
as the prototype. Based on first-principles calculations using the
nonequilibrium Green's function method combined with density functional theory,
we theoretically investigate the spin-resolved electronic transport properties
of this AMFTJ. By manipulating the various possible magnetization directions of
the multilayer antiferromagnetic MnBi$_2$Te$_4$ and the ferroelectric
polarization direction of the In$_2$Se$_3$ within the junction, sixteen
distinct non-volatile resistance states can be revealed and manipulated by
applying external biaxial strain and bias voltage. We predict maximum tunneling
magnetoresistance (electroresistance) values of $3.79\times10^{4}$\%
($2.41\times10^{5}$\%) in the equilibrium state, which can increase up to
$5.01\times10^{5}$\% ($4.97\times10^{5}$\%) under external bias voltage.
Furthermore, the perfect spin filtering effect is also present in our AMFTJ.
Our results highlight the tremendous potential of the MBT-2L/IS/MBT-2L vdW
AMFTJ in non-volatile memory, expanding the application avenues for
antiferromagnetic spintronic devices.
