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First-principle study on honeycomb fluorated-InTe monolayer with large Rashba spin splitting and direct bandgap
摘要： Rashba e?ect is much related to next-generation spintronic devices. It is highly desirable to search for Rashba materials with large Rashba spin splitting, which is considered as the key factor for the application of spin ?eld-e?ect transistor. Here, we design a two-dimensional monolayer of ?uorated-InTe (InTeF) with large Rashba spin splitting and direct bandgap on the basis of ?rst-principles calculations. InTeF monolayer is energetically and dynamically stable based on the calculations of cohesive energy and phonon dispersion. Remarkably, the Rashba parameter αR is about 1.08 eV·?, comparable to that of the BiTeI monolayer (1.86 eV·?). The direct bandgap is estimated to be 2.48 eV by HSE06 hybrid functional, which shows good prospects in light-emitting devices and photodetectors. To further explore the e?ect of substrates on the electronic structure of InTeF monolayer, we build two heterostructures, and the results show that the strength of Rashba e?ect and the direct bandgap nature in InTeF monolayer can be well preserved under the in?uence of substrates. Based on the above ?ndings in our work, InTeF monolayer is considered to be one of the promising 2D materials for the application of spintronics as well as optoelectronics.
关键词： Rashba spin splitting,InTeF monolayer,First-principle calculation,Direct bandgap
更新于2025-09-23 15:22:29
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Electronic structure of graphene nanoribbons on hexagonal boron nitride
摘要： Hexagonal boron nitride is an ideal dielectric to form two-dimensional heterostructures due to the fact that it can be exfoliated to be just a few atoms thick and its very low density of defects. By placing graphene nanoribbons on high quality hexagonal boron nitride it is possible to create ideal quasi-one-dimensional systems with very high mobility. The availability of high quality one-dimensional electronic systems is of great interest also given that when in proximity to a superconductor they can be effectively engineered to realize Majorana bound states. In this work we study how a boron nitride substrate affects the electronic properties of graphene nanoribbons. We consider both armchair and zigzag nanoribbons. Our results show that for some stacking configurations the boron nitride can significantly affect the electronic structure of the ribbons. In particular, for zigzag nanoribbons, due to the lock between spin and sublattice degree of freedom at the edges, the hexagonal boron nitride can induce a very strong spin splitting of the spin-polarized, edge states. We find that such spin splitting can be as high as 40 meV.
关键词： heterostructures,graphene nanoribbons,hexagonal boron nitride,spin splitting,electronic structure
更新于2025-09-23 15:21:21
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First-principles theory of giant Rashba-like spin splitting in bulk GeTe
摘要： Large Rashba-like spin splitting has been recently found in the band structure of certain bulk ferroelectrics. In contrast to the relativistic Rashba effect, the chiral spin texture and large spin splitting of the electronic bands depend strongly on the character of the band and atomic spin-orbit coupling. We establish that this can be traced back to an interplay between the orbital angular momentum and ferroelectricity. The additional dependence on the orbital composition of the bands is crucial to the complete picture of the effect. Results from ?rst-principles calculations on ferroelectic GeTe verify the key predictions of the model.
关键词： Rashba-like spin splitting,orbital angular momentum,ferroelectricity,spin-orbit coupling,GeTe
更新于2025-09-23 15:21:01
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Engineering Point Defect States in Monolayer WSe <sub/>2</sub>
摘要： Defect engineering is a key approach for tailoring the properties of the emerging two-dimensional semiconductors. Here, we report an atomic engineering of the W vacancy in monolayer WSe2 by single potassium atom decoration. The K decoration alters the energy states and reshapes the wave-function such that previously hidden mid-gap states become visible with well-resolved multiplets in scanning tunneling spectroscopy. Their energy levels are in good agreement with first principle calculations. More interestingly, the calculations show that an unpaired electron donated by the K atom can lead to a local magnetic moment, exhibiting an on-off switching by the odd-even number of electron filling. Experimentally the Fermi level is pinned above all defect states due to the graphite substrate, corresponding to an off state. The close agreement between theory and experiment in the off state, on the other hand, suggest a possibility of gate-programmable magnetic moments at the defects.
关键词： mid-gap defect states,spin splitting,defect engineering,local magnetic moment,transition metal dichalcogenides
更新于2025-09-19 17:15:36
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Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || In or Out of Control? Electron Spin Polarization in Spin-Orbit-Influenced Systems
摘要： Spintronics is the key word to motivate studies of spin-polarized electronic states in solids and at surfaces or interfaces. The use of the electron spin in addition to the electron charge as information carrier—that is the goal for spintronics devices. The generation, manipulation, and detection of spin-polarized currents promise applications in information technology. However, in many materials, the electronic states are spin degenerate. The spin degeneracy may be lifted by two interactions: (i) exchange interaction in magnetically ordered materials, where the magnetization direction is the reference for the alignment of the spin magnetic moments. Independent of location and momentum, the electron spin magnetic moment is either aligned parallel to the magnetization direction (majority spin, lower in energy) or antiparallel to it (minority, higher in energy), leading to a spin-dependent energy splitting, called exchange splitting, of the bands; (ii) spin–orbit interaction (SOI), which is present in all materials but becomes relevant in systems with high atomic number. In ferromagnets, SOI enables hybridization between bands of different spin character, leading to spin–orbit-induced energy gaps, sometimes called spin hot spots in the band structure, which are held responsible for demagnetization processes. Furthermore, noncollinear magnetic structures such as skyrmions arise from SOI in ferromagnets. In nonferromagnets, SOI leads to energy splitting of bands with different total angular momentum j but not necessarily to spin-split bands. Only in systems, where inversion symmetry is broken, which is, for example, the case at surfaces, the bands exhibit a spin-dependent energy splitting, which itself depends on the momentum k. This so-called Rashba-type spin splitting was predicted for a two-dimensional electron gas and experimentally observed in surface states on heavy metal surfaces, for example, Au(111) and W(110). The spin-dependent splitting depends on the momentum parallel to the surface kk and reverses its sign upon a sign change of kk. As a consequence, no net magnetic moment is formed. In contrast to Rashba systems, where surface states become spin split by SOI, topological insulators such as Bi2Se3 exhibit so-called topological surface states (TSS), which only appear as a consequence of SOI. SOI is responsible for band inversion and formation of a gap, which is then closed by a surface state with Dirac-cone-like energy dispersion and characteristic spin texture.
关键词： Rashba-type spin splitting,Spin–orbit interaction,Dirac-cone-like energy dispersion,Topological surface state,Spintronics
更新于2025-09-09 09:28:46
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surface alloy
摘要： We have investigated the atomic and electronic structure of the (√3×√3)R30? SnAu2/Au(111) surface alloy. Low-energy electron diffraction and scanning tunneling microscopy measurements show that the native herringbone reconstruction of bare Au(111) surface remains intact after formation of a long-range ordered (√3×√3)R30? SnAu2/Au(111) surface alloy. Angle-resolved photoemission and two-photon photoemission spectroscopy techniques reveal Rashba-type spin-split bands in the occupied valence band with comparable momentum space splitting as observed for the Au(111) surface state, but with a hole-like parabolic dispersion. Our experimental findings are compared with density functional theory (DFT) calculation that fully support our experimental findings. Taking advantage of the good agreement between our DFT calculations and the experimental results, we are able to extract that the occupied Sn-Au hybrid band is of (s, d )-orbital character, while the unoccupied Sn-Au hybrid bands are of (p, d )-orbital character. Hence we can conclude that the Rashba-type spin splitting of the hole-like Sn-Au hybrid surface state is caused by the significant mixing of Au d with Sn s states in conjunction with the strong atomic spin-orbit coupling of Au, i.e., of the substrate.
关键词： angle-resolved photoemission spectroscopy,density functional theory,SnAu2/Au(111) surface alloy,Rashba-type spin splitting,two-photon photoemission spectroscopy
更新于2025-09-09 09:28:46
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Spin splitting in EuO(111)/Si(111) spin-filter tunnel junctions with atomically sharp interface
摘要： We demonstrate the tunneling in spin-split barriers made of ferromagnetic EuO grown on Si(111) substrates by molecular beam epitaxy. For 6 nm thick EuO films with high crystal quality and atomically sharp interfaces, we find a barrier height lowering driven by the spin splitting below the Curie temperature of 35 K. We determined the splitting energy to be 0.56 + 0.03 eV at 20 K which results in a spin polarization above 90%.
关键词： molecular beam epitaxy,atomically sharp interface,EuO(111)/Si(111),spin splitting,spin-filter tunnel junctions
更新于2025-09-04 15:30:14
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Charge and spin transport anisotropy in nanopatterned graphene
摘要： Anisotropic electronic transport is a possible route towards nanoscale circuitry design, particularly in two-dimensional materials. Proposals to introduce such a feature in patterned graphene have to date relied on large-scale structural inhomogeneities. Here we theoretically explore how a random, yet homogeneous, distribution of zigzag-edged triangular perforations can generate spatial anisotropies in both charge and spin transport. Anisotropic electronic transport is found to persist under considerable disordering of the perforation edges, suggesting its viability under realistic experimental conditions. Furthermore, controlling the relative orientation of perforations enables spin ?ltering of the transmitted electrons, resulting in a half-metallic anisotropic transport regime. Our ?ndings point towards a co-integration of charge and spin control in a two-dimensional platform of relevance for nanocircuit design. We further highlight how geometrical effects allow ?nite samples to display ?nite transverse resistances, reminiscent of Spin Hall effects, in the absence of any bulk ?ngerprints of such mechanisms, and explore the underlying symmetries behind this behaviour.
关键词： zigzag edge magnetism,antidots,perforations,spintronics,anisotropic transport,graphene,spin splitting
更新于2025-09-04 15:30:14