Perfect Spin Filtering Effect on Fe₃GeTe₂-Based Van der Waals Magnetic Tunnel Junctions

Abstract

Conventional magnetic tunnel junctions (MTJs) face many issues in experiments and cannot meet a human’s urgent demand. Thus, van der Waals (vdW) MTJs increase in response to the proper time and conditions. By employing the combination of density functional theory (DFT) with the nonequilibrium Green’s function (NEGF) methods, Fe3GeTe2|InSe|Fe3GeTe2 vdW MTJs is proposed for the first time. Fe3GeTe2 has proven to be an excellent electrode for vdW MTJ applications, which shows a nature metallic FM characteristic with a high Curie temperature. Furthermore, semiconductor InSe with high electron mobility, a quantum Hall effect, and high stability is selected to be used as a tunneling barrier without lattice mismatching. Our designed MTJs show equal ability as a spin up and spin down filter. One can obtain a different spin-directional current only by changing the bias polarity without very high purity addition. Furthermore, a high tunnel magnetoresistance (TMR) ratio can reach up to ∼700%. The physical mechanisms behind this interesting phenomenon are given by analyzing k||-resolved transmission spectra and a complex band structure. Our results would provide theoretical foundation for designing two-dimensional spintronic logic, ultrafast magnetodynamics devices and information storage for new generation computer devices.