Three-Dimensional Electron Realm in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>VSe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>by Soft-X-Ray Photoelectron Spectroscopy: Origin of Charge-Density Waves

Strocov, Vladimir N.; Shi, M.; Kobayashi, Masaki; Monney, Claude; Wang, Xiaoqiang; Krempaský, Juraj; Schmitt, Thorsten; Patthey, L.; Berger, H.; Blaha, Peter

doi:10.1103/physrevlett.109.086401

Cited by 174 publications

(157 citation statements)

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“…The choice of this experimental technique was dictated by the larger photoelectron mean free path and thus bulk sensitivity compared to the conventional VUV-ARPES as well as concomitant sharp definition of the surface-perpendicular momentum k z . 39,40 The measured Fermi surface (FS) broadly agrees with previous experiments in (001) films and consists of an electron pocket at the Brillouin zone (BZ) center surrounded by eight hole pockets centered at the BZ corners. 9,10,41 We find that a simple two-band model of the Ni e g states assuming a cubic BZ does not fully describe the electronic structure whereas density functional theory (DFT) calculations including the bulk octahedral tilt pattern closely resemble the experimental Fermi surfaces providing a solid base for our observations.…”

confidence: 74%

Electronic structure of buried LaNiO3 layers in (111)-oriented LaNiO3/LaMnO3 superlattices probed by soft x-ray ARPES

et al. 2017

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Taking advantage of the large electron escape depth of soft x-ray angle resolved photoemission spectroscopy we report electronic structure measurements of (111)oriented [LaNiO3/LaMnO3] superlattices and LaNiO3 epitaxial films. For thin films we observe a 3D Fermi surface with an electron pocket at the Brillouin zone center and hole pockets at the zone vertices. Superlattices with thick nickelate layers present a similar electronic structure. However, as the thickness of the LaNiO3 is reduced the superlattices become insulating. These heterostructures do not show a marked redistribution of spectral weight in momentum space but exhibit a pseudogap of ≈ 50 meV. Main TextWith the advancement of synthesis techniques it is possible nowadays to control the growth of transition metal oxide (TMO) epitaxial heterostructures at the unit cell level. The realization of such heterostructures have resulted in the discovery of fascinating phenomena as a consequence of the confinement of strongly correlated electrons in ultrathin high quality layers. [1-3] Since these thin layers are embedded in heterostructures, interfacial phenomena such as charge transfer and magnetic coupling play an important role together with dimensionality in determining the ground state of the system. [4-8] The recent development of combined angle-resolved photoemission spectroscopy (ARPES) and oxide heterostructures growth setups has allowed the electronic structure of TMO heterostructures to be probed directly.

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confidence: 74%

Electronic structure of buried LaNiO3 layers in (111)-oriented LaNiO3/LaMnO3 superlattices probed by soft x-ray ARPES

et al. 2017

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“…1c) we report the k z evolution of the Fermi surface spanning about 9 Brillouin zones in the out-of-plane reciprocal direction and about 3 in-plane Brillouin zones along the W chain direction k x . Our measurements unambiguously unveil a clear continuous k z dispersion of the electronic states at the Fermi level, definitely proving that WTe 2 has a 3D bulk electronic structure despite the layered geometry common to all TMDs [12], and despite the preferential direction for electronic dispersion given by the zigzag TM chains. These results provide a spectroscopic validation of the early conclusions based on quantum oscillations experiments [6].…”

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confidence: 59%

“…By measuring ARPES with photon energy hν in the range 400-800 eV, one probes the electron states averaging on several layers and therefore reducing the weight of the surface specific features that otherwise dominate when excitations energies in the VUV-range are employed. Furthermore, the increase of photoelectron mean free path in the soft-X-ray energy range results in a high intrinsic k z resolution of the ARPES experiment [12], essential to explore 3D effects in electronic band structure.…”

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confidence: 99%

Three-Dimensional Electronic Structure of the Type-II Weyl Semimetal WTe2

et al. 2017

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By combining bulk sensitive soft-X-ray angular-resolved photoemission spectroscopy and accurate first-principles calculations we explored the bulk electronic properties of WTe2, a candidate type-II Weyl semimetal featuring a large non-saturating magnetoresistance. Despite the layered geometry suggesting a two-dimensional electronic structure, we find a three-dimensional electronic dispersion. We report an evident band dispersion in the reciprocal direction perpendicular to the layers, implying that electrons can also travel coherently when crossing from one layer to the other. The measured Fermi surface is characterized by two well-separated electron and hole pockets at either side of the Γ point, differently from previous more surface sensitive ARPES experiments that additionally found a significant quasiparticle weight at the zone center. Moreover, we observe a significant sensitivity of the bulk electronic structure of WTe2 around the Fermi level to electronic correlations and renormalizations due to self-energy effects, previously neglected in first-principles descriptions.Introduction -The observation of unconventional transport properties in WTe 2 [1], such as the large non-saturating magnetoresistance with values among the highest ever reported, prompted experiments and theory to address the electronic structure of this semimetallic transition metal dichalcogenides (TMD) [2][3][4][5][6]. WTe 2 consists of layers of transition metal (TM) atoms sandwiched between two layers of chalcogen atoms, similarly to other TMDs such as MoS 2 and MoSe 2 . Because of the layered structure, TMDs have commonly been considered as quasi-two-dimensional solids. The easiness of exfoliation down to a single layer makes them appealing for nanoscale electronic applications. WTe 2 has also been theoretically described, in a recent paper, as the prototypical system to host a new topological state of matter called type-II Weyl semimetal [7]. At odds with standard type-I Weyl semimetals showing a point-like Fermi surface, type-II Weyl excitations arise at the contact between hole and electron pockets. Theoretical predictions were immediately followed by several surface sensitive angle-resolved photoemission (ARPES) studies claiming evidence of topological Fermi arcs [8][9][10].

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“…As the photoelectrons excited by VUV light have a mean free path on the order of a few ångströms, we detect the electronic states only in the disordered layer in the VUV ARPES experiments. By contrast, the photoelectrons excited by soft x-ray light have a much longer mean free path 33 , and therefore using soft x-ray ARPES we are able to detect the well-defined band structure in the ordered lattice beneath the disordered layer.…”

Section: Nature Physicsmentioning

confidence: 93%