Robust Giant Magnetoresistance in 2D Van der Waals Molecular Magnetic Tunnel Junctions

Abstract

The spin transport across a zero-dimensional (0D) single-molecule sandwiched by two-dimensional (2D) van der Waals (vdW) ferromagnetic electrodes may open vast opportunities to create novel mixed-dimensional spintronics devices. However, this remains unexplored yet. Inspired by the recent discovery of 2D intrinsic ferromagnets Fe3GeTe2, using first-principles spin transport calculations, we show that single-molecule junctions based on Fe3GeTe2 can yield perfect spin filtering and a significant magnetoresistance (MR) of up to ∼6075%. This remarkable MR is more than 2 orders of magnitude higher than the MR obtained for the corresponding junctions with conventional ferromagnetic metals (e.g., Ni, Fe, and Co). We demonstrate the results of two representative examples that are feasible in the experiments: (i) A benzene or (ii) bezenedithiol (BDT) connected either through a scanning tunneling microscope or break-junction setups. We find that the conductance of BDT junctions is more than 10 times larger than that of the benzene junction due to a much stronger hybridization effect at the molecule–metal interfaces. The key mechanism of the perfect spin filtering and large MR in single-molecule junctions is mainly determined by the intrinsic properties of Fe3GeTe2 electrodes, while the actual conductance is determined by the hybridization strength of the majority spin channel at the molecule–metal interfaces. It is also predicted that the perfect spin filtering and the remarkably huge MR are highly insensitive to structural variations, interface defects, and stacking orders of the electrodes. Our results provide important insights for expanding molecular spintronics platforms from conventional ferromagnetic metals to new 2D vdw magnets.

Giant magnetoresistance in spin valves realized by substituting Y-site atoms in Heusler lattice

“…MR op is the general definition of MR ratio [54] which can be compared with the one reported in other literature [53,55,56]. At E F , the theoretical MR op is close to 10 10 % which is much larger than 10 6 % reported before [53].…”

Spin filtering and magnetoresistance effects in a dithiane ultra-short single-molecule insulator

“…12,13 With the discovery of many halfmetallic 2D materials in recent years, 18,19,21,22 it is worth expecting that MR could be further enhanced when dithiane is coupled to novel 2D ferromagnetic electrodes with high spinpolarization. 44…”

Strain-Induced Interlayer Magnetic Coupling Spike of the Two-Dimensional van der Waals Material Fe5GeTe2

“…Magnetism in two-dimensional (2D) van der Waals (vdW) materials has attracted enormous attention in technological advances as its potential application ranges from topological magnonics to low-power spintronics and quantum computing. − Among the families of 2D vdW materials, Fe 5 GeTe 2 (F5GT) is a newly synthesized and promising vdW ferromagnet for spintronic devices due to its high Curie temperature (about 293 K) and novel spintronic properties. , Strain engineering is an exciting and feasible method to manipulate the properties of materials in both theoretical and experimental investigations, which creates various opportunities for the study of new fundamental physics and applications of 2D vdW materials. − Meanwhile, 2D vdW materials were often transferred or grown onto a substrate such that the strain can be introduced by the substrate . It has been observed that the magnetic properties of vdW materials are sensitive to the applied strain. − …”

“…A theoretical investigation of the strained single-layer F5GT has been reported . However, spintronic devices are mainly based on multilayer vdW materials or heterostructures, such as giant magnetoresistance (GMR) and tunneling magnetoresistance (TMR) − devices. The presence of interlayer coupling could dramatically change the performance of devices. , Interlayer coupling can be divided into two parts, i.e., interlayer chemical coupling (ILCC) and interlayer magnetic coupling (ILMC), which is of significance in terms of multilayer spintronics. , Numerous publications have demonstrated the continuous evolution of ILMC, even in the context of magnetic phase change. , The discontinuous transition feature in ILMC could encourage new avenues of research in spintronic devices.…”