Large Perpendicular Magnetic Anisotropy in Ta/CoFeB/MgO on Full-Coverage Monolayer MoS₂ and First-Principles Study of Its Electronic Structure

Abstract

Perpendicularly magnetized spin injector with high Curie temperature is a prerequisite for developing spin optoelectronic devices on 2D materials working at room temperature (RT) with zero applied magnetic field. Here, we report the growth of Ta/CoFeB/MgO structures with a large perpendicular magnetic anisotropy (PMA) on full coverage monolayer (ML) MoS2. A large perpendicular interface anisotropy energy of 0.975mJ/m 2 has been obtained at the CoFeB/MgO interface, comparable to that observed in magnetic tunnel junction systems. It is found that the insertion of MgO between the ferromagnetic metal (FM) and the 2D material can effectively prevent the diffusion of the FM atoms into the 2D material. Moreover, the MoS2 ML favors a MgO(001) texture and plays a critical role to establish the large PMA. First principle calculations on a similar Fe/MgO/MoS2 structure reveal that the MgO thickness can modify the MoS2 band structure, from an indirect bandgap with 7ML-MgO to a direct bandgap with 3ML-MgO. Proximity effect induced by Fe results in a splitting of 10meV in the valence band at the Γ point for the 3ML-MgO structure while it is negligible for the 7ML-MgO structure. These results pave the way to develop RT spin optoelectronic devices on 2D transition-metal dichalcogenide materials.

Tunable tunneling magnetoresistance in in-plane double barrier magnetic tunnel junctions based on B vacancy h-NB nanoribbons

“…Magnetic tunnel junctions (MTJs) with ferromagnet/insulator/ferromagnet sandwiches are still attracting significant scientific and technological interest 1–6 after they were proposed forty years ago due to their capability to be employed in magnetic read heads, magnetic random-access memories (MRAM), magnetic sensors and in-memory computing. However, with the development of information technology, traditional MTJs based on CoFeB and MgO have been unable to meet the performance requirements of ultra-high integration, ultra-low power consumption and ultra-high speed that next-generation spintronic devices must have.…”

Defect-Density- and Rashba-Shift-Induced Interfacial Dzyaloshinskii–Moriya Interaction and Spin Pumping in Single-Layer Graphene/Co20Fe60B20 Heterostructures: Implications for New-Generation Spintronics

“…These include interfacial perpendicular magnetic anisotropy (iPMA), the Rashba effect, spin pumping, the spin Hall effect, and interfacial Dzyaloshinskii–Moriya interaction (iDMI), , to name a few. However, most interfacial phenomena are associated with a large spin–orbit coupling (SOC), and because the SOC is proportional to Z 4 ( Z = atomic number), heavy metals (HMs) are the natural choice for the nonmagnetic layer. − Recently, two-dimensional (2D) materials, such as graphene, MoS 2 , and topological insulators, have shown promise in engineering interface magnetism. ,− Graphene, a monolayer of carbon atoms, shows a prolonged spin relaxation time (approximately microseconds) and a long spin diffusion length (approximately micron), − which lead to long-distance propagation of the spin angular momentum through this material. In addition, graphene has many other interesting properties, such as high electron mobility, massless linear electronic dispersion, low resistivity, gate-controllable spin transport in a spin-valve device, weak hyperfine interaction, etc., that promote graphene as an attractive material for new-generation nanoscale and energy-efficient spintronics.…”