Abstract
The possibility to achieve charge-to-spin conversion via Rashba spin–orbit effects provides stimulating opportunities toward the development of nanoscale spintronics. Here, we use first-principles calculations to study the electronic and spintronic properties of Tl2O/PtS2 heterostructure, for which we have confirmed the dynamical stability by its positive phonon frequencies. An unexpectedly high binding energy of −0.38 eV per unit cell depicts strong interlayer interactions between Tl2O and PtS2. Interestingly, we discover Rashba spin-splittings (with a large αR value) in the valence band of Tl2O stemming from interfacial spin–orbit effects caused by PtS2. The role of van der Waals binding on the orbital rearrangements has been studied using the electron localization function and atomic orbital projections, which explains in detail the electronic dispersion near the Fermi level. Moreover, we explain the distinct band structure alignment in momentum space but separation in real space of Tl2O/PtS2 heterostructure. Since two-dimensional (2D) Tl2O still awaits experimental confirmation, we calculate, for the first time, the Raman spectra of pristine Tl2O and the Tl2O/PtS2 heterostructure and discuss peak positions corresponding to vibrational modes of the atoms. These findings offer a promising avenue to explore spin physics for potential spintronics applications via 2D heterostructures.
Highlights
Spin−orbit effects in two-dimensional (2D) materials are of central importance for designing next-generation spintronic, valleytronic, and spin-logic memory devices
Transition-metal dichalcogenides (TMDCs) such as MoS2, in their pristine form and in proximity to other 2D materials, have been extensively utilized in such applications owing to their large spin−orbit strength and other promising features.[1−4] In this context, the Rashba spin−orbit effects are of particular interest because they enable charge-to-spin conversion in a non-magnetic material by lifting spin degeneracy along the momentum axis without the need of an external magnetic field.[5,6]
Owing to the importance of spin generation, detection, and manipulation in a typical spintronics device, our results provide a promising platform to harness the spin degree of freedom in 2D heterostructures by employing interfacial spin−orbit effects
Summary
Spin−orbit effects in two-dimensional (2D) materials are of central importance for designing next-generation spintronic, valleytronic, and spin-logic memory devices. Monolayer Tl2O is a recently proposed 2D metal-oxide semiconductor with cleavage energy comparable to well-known TMDCs.[30] Several theoretical studies highlighted its potential in catalysis,[31] valleytronics,[32] and especially in thermoelectrics[33,34] due to the ultralow lattice thermal conductivity.[35] Bulk Tl2O crystallizes in the 1T-phase with its cousin polytype existing in 2H-phase albeit higher in energy[36] favoring the synthesis of the former due to energetic reasons. While 2D Tl2O still awaits experimental realization, a 2D thallene was recently fabricated on a NiSi2/Si(111) substrate experiencing a strong tensile strain due to the large lattice mismatch.[37] It is extremely critical to select an appropriate material capable to host Tl2O in its most stable form
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