Abstract
Recently, the study on two-dimensional materials expands to the field of spintronics. The intrinsically ferromagnetic van der Waals materials such as CrI3 and CrBr3 receive much attention due to nearly 100% spin polarization and good stability, resulting in excellent performance in magnetic tunnel junctions. In this work, we design the magnetic tunnel junctions of Cu/CrI3/Cu and Cu/CrBr3/Cu with the electrodes of Cu(111) and the tunneling barrier of 4-monolayer CrI3 or CrBr3. Our first-principle calculations combined with nonequilibrium Green’s function method indicate that the CrBr3-based MTJ has a larger maximum tunneling magnetoresistance ratio than the CrI3-based MTJ. In a wide bias voltage range, the CrI3-based MTJ can maintain high spin filtering performance, while that of the CrBr3-based MTJ degrades sharply as the bias voltage increases. It is noted that negative differential resistance effect is observed in the CrBr3-based MTJ. The differences of spin transport properties between the CrI3-based MTJ and the CrBr3-based MTJ are clarified in terms of the inside device physics, including the spin-dependent projected density of states, band structures, Bloch states, and the electron density difference. This work provides some physical insights for the design of 2D van der Waals MTJ.
Strength of the symmetry spin-filtering effect in magnetic tunnel junctions