The Rashba effect in several surface systems, Au(111), Au(110), Ag(111), Sb(111) and Si(111)-Bi, is studied by means of first-principles relativistic density-functional calculations. The importance of the asymmetric behavior around the surface atom is emphasized as a crucial factor to determine the magnitude of Rashba spin splitting in addition to the size of the spin-orbit coupling. The Rashba effect at the Brillouin-zone boundary is generally described with time-reversal symmetry. Distinctive features in the spin splitting and spin direction for a two-dimensional hexagonal system are discussed with the use of symmetry in the double group of k.
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http://dx.doi.org/10.1088/0953-8984/21/6/064239 | DOI Listing |
Phys Chem Chem Phys
January 2025
Ronin Institute, Montclair, New Jersey 07043, USA.
The Rashba effect in a nonmagnetic condensed-matter system is described by the reduction of point-group symmetries. The inversion, two-fold rotation, and reflection symmetries transforming the wavevector to - are identified as the origin of a degenerate state according to the time-reversal symmetry. The lack of these symmetries in a bulk system or the breaking of these in a surface system is then identified as the origin of a nondegenerate state.
View Article and Find Full Text PDFAdv Mater
January 2025
Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea.
Magnetization switching by charge current without a magnetic field is essential for device applications and information technology. It generally requires a current-induced out-of-plane spin polarization beyond the capability of conventional ferromagnet/heavy-metal systems, where the current-induced spin polarization aligns in-plane orthogonal to the in-plane charge current and out-of-plane spin current. Here, a new approach is demonstrated for magnetic-field-free switching by fabricating a van-der-Waals magnet and oxide FeGeTe/SrTiO heterostructure.
View Article and Find Full Text PDFACS Nano
January 2025
Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan.
We have found that surface superstructures made of "monolayer alloys" of Tl and Pb on Si(111), having giant Rashba effect, produce nonreciprocal spin-polarized photocurrent via circular photogalvanic effect (CPGE) by obliquely shining circularly polarized near-infrared (IR) light. CPGE is here caused by the injection of in-plane spin into spin-split surface-state bands, which is observed only on Tl-Pb alloy layers but not on single-element Tl nor Pb layers. In the Tl-Pb monolayer alloys, despite their monatomic thickness, the magnitude of CPGE is comparable to or even larger than the cases of many other spin-split thin-film materials.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
Understanding and manipulating magnetic damping, particularly in magnetic heterostructures, is crucial for fundamental research, versatile engineering, and optimization. Although magnetic damping can be enhanced by the band hybridization between ferromagnetic and nonmagnetic materials at the interface, the contribution of individual subbands on the hybridized bands to magnetic damping is fully unexplored. Here, it is found that magnetic damping α is modified by the Fermi level in Fe/GeTe heterostructures via Bi doping.
View Article and Find Full Text PDFACS Nano
December 2024
Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, U.K.
Interaction between electrons and phonons in solids is a key effect defining the physical properties of materials, such as electrical and thermal conductivity. In transition metal dichalcogenides (TMDCs), the electron-phonon coupling results in the formation of polarons, quasiparticles that manifest themselves as discrete features in the electronic spectral function. In this study, we report the formation of polarons at the alkali-dosed MoSe surface, where Rashba-like spin splitting of the conduction band states is caused by an inversion-symmetry breaking electric field.
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