Density functional and Monte Carlo investigation of FeNi/MoS2 junction

In this paper, first principles computations are performed to investigate structural, electronic, magnetic, and thermodynamic properties of a novel two-dimensional ferromagnet/semiconductor junction, consisting of a monolayer of FeNi on a single monolayer of ${\mathrm{MoS}}_{2}$. After investigating more than 30 different arrangements of Fe and Ni atoms on ${\mathrm{MoS}}_{2}$, it is concluded that Ni-S bonding is more likely at the FeNi/${\mathrm{MoS}}_{2}$ interface, while highly spin polarized Fe atoms prefer to stay well above the ${\mathrm{MoS}}_{2}$ monolayer, forming a zigzag FeNi layer at the surface. Accurate investigation of the electronic structure of the most stable configuration of FeNi/${\mathrm{MoS}}_{2}$ junction evidences appearance of some majority and minority surface charge carriers with very different mobilities, predicting a high spin polarized conductivity in the junction. Tens of different spin orderings are applied to the FeNi monolayer in a $3\ifmmode\times\else\texttimes\fi{}3$ supercell to achieve reliable Heisenberg exchange constants for parametrization of the magnetic energy of the FeNi/${\mathrm{MoS}}_{2}$ junction. The obtained exchange constants are then used for classical Monte Carlo simulation of magnetic thermodynamic properties of the system, including magnetic order parameter, heat capacity, and magnetic susceptibility. The predicted very high paramagnetic transition temperature ($g1300\phantom{\rule{0.28em}{0ex}}\text{K}$) along with the speculated high spin polarized conductivity evidences potential application of this junction in spintronics.