The goal of this proposal is to theoretically and numerically study the quantum transport properties of novel 2D magnetic materials, which are potential candidates for the next-generation electronic and magnetic industry. The calculations of magnetoresistance of huge systems with thousands of atoms by ab initio quantum transport theory in a controllable way is quite challenging. In this project, first, we will study the stability of the materials using phonon calculations. Next, the transport calculations for the electrodes and devices with many numbers of atoms will be done using Siesta and Transiesta packages. 2D metallic magnets such as Fe$_n$GeTe$_2$ (n=3,4,5) will be considered. Moreover, magnetoresistance and quantum transport properties in the presence of external disorder, magnetic field and laser irradiation will be calculated with tight-binding Hamiltonian generated from density functional theory calculations and Wannierization of Kohn-Sham orbitals. Several ab initio packages and state-of-the-art codes will be used for this project.