scholarly journals Angle-resolved photoemission spectroscopy of the metallic sodium tungsten bronzesNaxWO3

2005 ◽  
Vol 72 (12) ◽  
Author(s):  
S. Raj ◽  
D. Hashimoto ◽  
H. Matsui ◽  
S. Souma ◽  
T. Sato ◽  
...  
Keyword(s):  
Photoemission Spectroscopy ◽  
Metallic Sodium ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Sodium Tungsten

scholarly journals METAL-INSULATOR TRANSITION OF NaxWO3 STUDIED BY ANGLE-RESOLVED PHOTOEMISSION SPECTROSCOPY

2009 ◽  
Vol 23 (24) ◽  
pp. 2819-2846 ◽  
Author(s):  
SATYABRATA RAJ ◽  
TAKAFUMI SATO ◽  
SEIGO SOUMA ◽  
TAKASHI TAKAHASHI ◽  
D. D. SARMA ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Fermi Level ◽  
Good Description ◽  
Tungsten Bronze ◽  
Insulator Transition ◽  
Photoemission Spectroscopy ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Sodium Tungsten

The electronic structure of sodium tungsten bronzes Na x WO 3 is investigated by high-resolution angle-resolved photoemission spectroscopy (ARPES). The ARPES spectra measured in both insulating and metallic phases of Na x WO 3 reveals the origin of metal-insulator transition (MIT) in sodium tungsten bronze system. It is found that in insulating Na x WO 3 the states near the Fermi level (EF) are localized due to the strong disorder caused by the random distribution of Na + ions in WO 3 lattice. Due to the presence of disorder and long-range Coulomb interaction of conduction electrons, a soft Coulomb gap arises, where the density of states vanishes exactly at EF. In the metallic regime the states near EF are populated and the Fermi level shifts upward rigidly with increasing electron doping (x). Volume of electron-like Fermi surface (FS) at the Γ(X) point of the Brillouin zone gradually increases with increasing Na concentration due to W 5d t2g band filling. A rigid shift of the Fermi energy is found to give a qualitatively good description of the Fermi surface evolution. As we move from bulk-sensitive to more surface sensitive photon energy, we found the emergence of Fermi surfaces at X(M) and M(R) points similar to the one at the Γ(X) point in the metallic regime, suggesting that the reconstruction of surface was due to rotation/deformation of WO 6 octahedra.

scholarly journals Evidence for a large Rashba splitting in PtPb4 from angle-resolved photoemission spectroscopy

2021 ◽  
Vol 103 (8) ◽  
Author(s):  
Kyungchan Lee ◽  
Daixiang Mou ◽  
Na Hyun Jo ◽  
Yun Wu ◽  
Benjamin Schrunk ◽  
...  
Keyword(s):  
Photoemission Spectroscopy ◽  
Angle Resolved Photoemission Spectroscopy

scholarly journals Observation of a singular Weyl point surrounded by charged nodal walls in PtGa

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
J.-Z. Ma ◽  
Q.-S. Wu ◽  
M. Song ◽  
S.-N. Zhang ◽  
E. B. Guedes ◽  
...  
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Photoemission Spectroscopy ◽  
Functional Theory ◽  
Fermi Arc ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Fermi Arcs ◽  
Surface Projection ◽  
Applicable Range ◽  
Opposite Chirality

AbstractConstrained by the Nielsen-Ninomiya no-go theorem, in all so-far experimentally determined Weyl semimetals (WSMs) the Weyl points (WPs) always appear in pairs in the momentum space with no exception. As a consequence, Fermi arcs occur on surfaces which connect the projections of the WPs with opposite chiral charges. However, this situation can be circumvented in the case of unpaired WP, without relevant surface Fermi arc connecting its surface projection, appearing singularly, while its Berry curvature field is absorbed by nontrivial charged nodal walls. Here, combining angle-resolved photoemission spectroscopy with density functional theory calculations, we show experimentally that a singular Weyl point emerges in PtGa at the center of the Brillouin zone (BZ), which is surrounded by closed Weyl nodal walls located at the BZ boundaries and there is no Fermi arc connecting its surface projection. Our results reveal that nontrivial band crossings of different dimensionalities can emerge concomitantly in condensed matter, while their coexistence ensures the net topological charge of different dimensional topological objects to be zero. Our observation extends the applicable range of the original Nielsen-Ninomiya no-go theorem which was derived from zero dimensional paired WPs with opposite chirality.

scholarly journals Emergent flat band electronic structure in a VSe2/Bi2Se3 heterostructure

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Turgut Yilmaz ◽  
Xiao Tong ◽  
Zhongwei Dai ◽  
Jerzy T. Sadowski ◽  
Eike F. Schwier ◽  
...  
Keyword(s):  
Dirac Point ◽  
Electronic States ◽  
Quantum States ◽  
Photoemission Spectroscopy ◽  
Flat Band ◽  
Strongly Correlated ◽  
Dirac Cone ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Topological Materials ◽  
Photoemission Study

AbstractFlat band electronic states are proposed to be a fundamental tool to achieve various quantum states of matter at higher temperatures due to the enhanced electronic correlations. However, materials with such peculiar electronic states are rare and often rely on subtle properties of the band structures. Here, by using angle-resolved photoemission spectroscopy, we show the emergent flat band in a VSe2 / Bi2Se3 heterostructure. Our photoemission study demonstrates that the flat band covers the entire Brillouin zone and exhibits 2D nature with a complex circular dichroism. In addition, the Dirac cone of Bi2Se3 is not reshaped by the flat band even though they overlap in proximity of the Dirac point. These features make this flat band distinguishable from the ones previously found. Thereby, the observation of a flat band in the VSe2 / Bi2Se3 heterostructure opens a promising pathway to realize strongly correlated quantum effects in topological materials.

Recent Advances in Topological Quantum Materials by Angle-Resolved Photoemission Spectroscopy

Matter ◽  
2020 ◽  
Vol 3 (4) ◽  
pp. 1114-1141
Author(s):  
Yujie Chen ◽  
Xu Gu ◽  
Yiwei Li ◽  
Xian Du ◽  
Lexian Yang ◽  
...  
Keyword(s):  
Photoemission Spectroscopy ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Recent Advances ◽  
Topological Quantum ◽  
Quantum Materials
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