Revealing flat bands near the Fermi level in 1T−VSe2 by using angle-resolved photoemission spectroscopy

2022 ◽  
Vol 105 (4) ◽  
Author(s):  
T. Yilmaz ◽  
E. Vescovo
Keyword(s):  
Fermi Level ◽  
Photoemission Spectroscopy ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Flat Bands

scholarly journals Sixfold fermion near the Fermi level in cubic PtBi2

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Setti Thirupathaiah ◽  
Y. S. Kushnirenk ◽  
Klaus Koepernik ◽  
B. R. Piening ◽  
Bernd Buechner ◽  
...  
Keyword(s):  
Fermi Level ◽  
Density Functional ◽  
Photoemission Spectroscopy ◽  
Functional Theory ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Ideal Candidate ◽  
Close Proximity ◽  
Weyl Semimetals ◽  
Crossing Point ◽  
Good Agreement

We show that the cubic compound PbBi2 is a topological semimetal hosting a sixfold band touching point in close proximity to the Fermi level. Using angle-resolved photoemission spectroscopy, we map the band structure of the system, which is in good agreement with results from density functional theory. Further, by employing a low energy effective Hamiltonian valid close to the crossing point, we study the effect of a magnetic field on the sixfold fermion. The latter splits into a total of twenty Weyl cones for a Zeeman field oriented in the diagonal, (111) direction. Our results mark cubic PbBi2 as an ideal candidate to study the transport properties of gapless topological systems beyond Dirac and Weyl semimetals.

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.

Low Energy Excitation in Bi2Sr2Can-1CunO2n+4 (n = 1-3) Studied by High-Resolution Arpes

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3554-3558
Author(s):  
H. Matsui ◽  
T. Sato ◽  
T. Takahashi ◽  
H.-B. Yang ◽  
S.-C. Wang ◽  
...  
Keyword(s):  
Electronic Structure ◽  
High Resolution ◽  
Fermi Level ◽  
Superconducting State ◽  
Low Energy ◽  
Photoemission Spectroscopy ◽  
Energy Excitation ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Arpes Data ◽  
Layered Cuprates

We report systematic high-resolution angle-resolved photoemission spectroscopy (ARPES) on Bi 2 Sr 2 Ca n-1 Cu n O 2n+4 (n = 1-3) to study the electronic structure near the Fermi level (EF) and the low energy excitation. Comprehensive ARPES data on the sudden break in the energy dispersion near EF (kink) as a function of momentum, temperature, and number of CuO 2 layers indicate that the coupling of electrons with Q = (π,π) magnetic mode is dominant in the superconducting state for multi-layered cuprates.

Near Fermi level electronic structure of Ti3SiC2 revealed by angle-resolved photoemission spectroscopy

2020 ◽  
Vol 102 (7) ◽  
Author(s):  
Damir Pinek ◽  
Takahiro Ito ◽  
Kanji Furuta ◽  
Youngsoo Kim ◽  
Masashi Ikemoto ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Fermi Level ◽  
Photoemission Spectroscopy ◽  
Angle Resolved Photoemission Spectroscopy

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.

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