Publications by authors named "Hendrik Bentmann"
Chiral crystals and molecules were recently predicted to form an intriguing platform for unconventional orbital physics. Here, we report the observation of chirality-driven orbital textures in the bulk electronic structure of CoSi, a prototype member of the cubic B20 family of chiral crystals. Using circular dichroism in soft x-ray angle-resolved photoemission, we demonstrate the formation of a bulk orbital-angular-momentum texture and monopolelike orbital-momentum locking that depends on crystal handedness.
View Article and Find Full Text PDFThe recent realizations of the quantum anomalous Hall effect (QAHE) in MnBi Te and MnBi Te benchmark the (MnBi Te )(Bi Te ) family as a promising hotbed for further QAHE improvements. The family owes its potential to its ferromagnetically (FM) ordered MnBi Te septuple layers (SLs). However, the QAHE realization is complicated in MnBi Te and MnBi Te due to the substantial antiferromagnetic (AFM) coupling between the SLs.
View Article and Find Full Text PDFSpatially controlling the Fermi level of topological insulators and keeping their electronic states stable are indispensable processes to put this material into practical use for semiconductor spintronics devices. So far, however, such a method has not been established yet. Here we show a novel method for doping a hole into n-type topological insulators BiX (X= Se, Te) that overcomes the shortcomings of the previous reported methods.
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- The Rashba effect is key to understanding two-dimensional electron systems and is crucial for various spintronic applications.
- This study provides strong experimental support for the idea that orbital angular momentum (OAM) in Bloch wave functions is responsible for the Rashba effect in a monolayer of AgTe on Ag(111).
- By employing advanced techniques like angle-resolved photoemission (ARPES) and low-energy electron diffraction, researchers establish a clear link between OAM and Rashba spin splittings in AgTe's electronic bands.
Article Synopsis
- TaAs and TaP are recognized as Weyl semimetals, but understanding their surface features and Fermi arcs related to their bulk Weyl points has been a challenge.
- * The study combines linear dichroism in angle-resolved photoemission with first-principles calculations to investigate the orbital texture on the Fermi surface of TaP(001).
- * The researchers identify distinct changes in orbital texture at Weyl nodes, demonstrating the importance of orbital degrees of freedom in connecting surface and bulk properties in Weyl semimetals.*
Semiconductors with strong spin-orbit interaction as the underlying mechanism for the generation of spin-polarized electrons are showing potential for applications in spintronic devices. Unveiling the full spin texture in momentum space for such materials and its relation to the microscopic structure of the electronic wave functions is experimentally challenging and yet essential for exploiting spin-orbit effects for spin manipulation. Here we employ a state-of-the-art photoelectron momentum microscope with a multichannel spin filter to directly image the spin texture of the layered polar semiconductor BiTeI within the full two-dimensional momentum plane.
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- - The study explores the relationship between the surface state of a Z(2) topological insulator and the bulk electronic structure, particularly focusing on Sb(2)Te(3)(0001) using photoemission experiments and calculations.
- - The topological surface state (TSS) exhibits distinct features, such as a consistent spectral signature and linear dispersion, even as it interacts with the topmost valence band.
- - Observations reveal a "kink" in the TSS dispersion and hybridization gaps, providing insight into the weak surface-bulk mixing seen in recent transport experiments on Sb(2)Te(3).
We report the direct observation of interband spin-orbit (SO) coupling in a two-dimensional (2D) surface electron system, in addition to the anticipated Rashba spin splitting. Using angle-resolved photoemission experiments and first-principles calculations on Bi-Ag-Au heterostructures, we show that the effect strongly modifies the dispersion as well as the orbital and spin character of the 2D electronic states, thus giving rise to considerable deviations from the Rashba model. The strength of the interband SO coupling is tuned by the thickness of the thin film structures.
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