  In our previous work, we synthesized a metal/2D material heterointerface
consisting of $L1_0$-ordered iron-palladium (FePd) and graphene (Gr) called
FePd(001)/Gr. This system has been explored by both experimental measurements
and theoretical calculations. In this study, we focus on a heterojunction
composed of FePd and multilayer graphene referred to as
FePd(001)/$m$-Gr/FePd(001), where $m$ represents the number of graphene layers.
We perform first-principles calculations to predict their spin-dependent
transport properties. The quantitative calculations of spin-resolved
conductance and magnetoresistance (MR) ratio (150-200%) suggest that the
proposed structure can function as a magnetic tunnel junction in spintronics
applications. We also find that an increase in $m$ not only reduces conductance
but also changes transport properties from the tunneling behavior to the
graphite $\pi$-band-like behavior. Additionally, we investigate the
spin-transfer torque-induced magnetization switching behavior of our
\color{blue} junction structures \color{black} using micromagnetic simulations.
Furthermore, we examine the impact of lateral displacements (``sliding'') at
the interface and find that the spin transport properties remain robust despite
these changes; this is the advantage of two-dimensional material
hetero-interfaces over traditional insulating barrier layers such as MgO.
