Abstract
Giant spin splitting (GSS) of electronic bands, which is several orders of magnitude greater than the standard Rashba effect has been observed in various systems including noble-metal surfaces and thin films of transition-metal dichalcogenides. Previous studies reported that orbital angular momentum (OAM) is not quenched in some GSS materials and that the atomic spin-orbit interaction (SOI) generates spin splitting in some solid states via the interorbital hopping. Although the unquenched OAM may be closely related to the interorbital hopping, their relationship is hardly studied in the aspect of using the unquenched OAM as a control parameter of GSS. Here, we analyze OAM in GSS materials by using the interorbital-hopping mechanism and first-principles calculations. We report that the interatomic hopping between different-parity orbitals, which is generated by specific broken mirror symmetry, produces k-dependent OAM, resulting in valley-dependent GSS in WSe2 monolayer, Rashba-type GSS in Au (111) surface, and Dresselhaus-type GSS in bulk HgTe. We also demonstrate systematic control of OAM by pressure, external fields, and substrates, thereby controlling the spin splitting, and discuss the temperature dependence of OAM. Our results provide a simplified picture for systematic design and control of GSS materials.
Highlights
Giant spin splitting (GSS) of electronic bands, which is several orders of magnitude greater than the standard Rashba effect has been observed in various systems including noble-metal surfaces and thin films of transition-metal dichalcogenides
When the inversion symmetry is broken, the spin-orbit interaction (SOI) can lift the degeneracy, generating an energy splitting[2,3,4,5]. This splitting is several orders greater than that in conventional materials, which is referred to as the giant spin splitting (GSS)[6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23]. Since it is promising for applications such as room-temperature spintronic devices, the interest in the phenomenon has been According to the Rashba model[4, 5], electrons moving in a increasing24. plane perpendicular to an external electric field
Once orbital angular momentum (OAM) is modified, GSS is modified. These results provide a simplified picture for systematic design and control of GSS materials
Summary
Giant spin splitting (GSS) of electronic bands, which is several orders of magnitude greater than the standard Rashba effect has been observed in various systems including noble-metal surfaces and thin films of transition-metal dichalcogenides. Previous studies reported that orbital angular momentum (OAM) is not quenched in some GSS materials and that the atomic spin-orbit interaction (SOI) generates spin splitting in some solid states via the interorbital hopping. When the inversion symmetry is broken, the spin-orbit interaction (SOI) can lift the degeneracy, generating an energy splitting[2,3,4,5] In some materials, this splitting is several orders greater than that in conventional materials, which is referred to as the giant spin splitting (GSS)[6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23]. In the study of ferroelectric halide perovskites using a similar framework[39], significance of OAM was more recognized
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