scholarly journals Robust doubly charged nodal lines and nodal surfaces in centrosymmetric systems

2017 ◽  
Vol 96 (15) ◽  
Author(s):  
Tomáš Bzdušek ◽  
Manfred Sigrist
Keyword(s):  
Nodal Lines ◽  
Doubly Charged ◽  
Nodal Surfaces

scholarly journals Linking structures of doubly charged nodal surfaces in centrosymmetric superconductors

2021 ◽  
Vol 103 (22) ◽  
Author(s):  
Sunje Kim ◽  
Dong-Choon Ryu ◽  
Bohm-Jung Yang
Keyword(s):  
Doubly Charged ◽  
Nodal Surfaces

scholarly journals Dirac nodal surfaces and nodal lines in ZrSiS

2019 ◽  
Vol 5 (5) ◽  
pp. eaau6459 ◽  
Author(s):  
B.-B. Fu ◽  
C.-J. Yi ◽  
T.-T. Zhang ◽  
M. Caputo ◽  
J.-Z. Ma ◽  
...  
Keyword(s):  
Photoemission Spectroscopy ◽  
Dirac Fermions ◽  
Fermi Surfaces ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Nodal Lines ◽  
Nodal Points ◽  
Different Dimensions ◽  
Topological Semimetals ◽  
Symmetry Protected ◽  
Nodal Surfaces

Topological semimetals are characterized by symmetry-protected band crossings, which can be preserved in different dimensions in momentum space, forming zero-dimensional nodal points, one-dimensional nodal lines, or even two-dimensional nodal surfaces. Materials harboring nodal points and nodal lines have been experimentally verified, whereas experimental evidence of nodal surfaces is still lacking. Here, using angle-resolved photoemission spectroscopy (ARPES), we reveal the coexistence of Dirac nodal surfaces and nodal lines in the bulk electronic structures of ZrSiS. As compared with previous ARPES studies on ZrSiS, we obtained pure bulk states, which enable us to extract unambiguously intrinsic information of the bulk nodal surfaces and nodal lines. Our results show that the nodal lines are the only feature near the Fermi level and constitute the whole Fermi surfaces. We not only prove that the low-energy quasiparticles in ZrSiS are contributed entirely by Dirac fermions but also experimentally realize the nodal surface in topological semimetals.

scholarly journals Observation of a topological nodal surface and its surface-state arcs in an artificial acoustic crystal

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yihao Yang ◽  
Jian-ping Xia ◽  
Hong-xiang Sun ◽  
Yong Ge ◽  
Ding Jia ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Surface States ◽  
Field Measurements ◽  
Wave System ◽  
Nodal Surface ◽  
Nodal Lines ◽  
Nodal Points ◽  
Higher Dimensional ◽  
Classical Wave ◽  
Nodal Surfaces

AbstractThree-dimensional (3D) gapless topological phases can be classified by the dimensionality of the band degeneracies, including zero-dimensional (0D) nodal points, one-dimensional (1D) nodal lines, and two-dimensional (2D) nodal surfaces. Both nodal points and nodal lines have been realized recently in photonics and acoustics. However, a nodal surface has never been observed in any classical-wave system. Here, we report on the experimental observation of a twofold symmetry-enforced nodal surface in a 3D chiral acoustic crystal. In particular, the demonstrated nodal surface carries a topological charge of 2, constituting the first realization of a higher-dimensional topologically-charged band degeneracy. Using direct acoustic field measurements, we observe the projected nodal surface and its Fermi-arc-like surface states and demonstrate topologically-induced robustness of the surface states against disorders. This discovery of a higher-dimensional topologically-charged band degeneracy paves the way toward further explorations of the physics and applications of new topological semimetal phases.

scholarly journals Prediction of unconventional magnetism in doped FeSb2

2021 ◽  
Vol 118 (42) ◽  
pp. e2108924118
Author(s):  
Igor I. Mazin ◽  
Klaus Koepernik ◽  
Michelle D. Johannes ◽  
Rafael González-Hernández ◽  
Libor Šmejkal
Keyword(s):  
Real Space ◽  
Orbit Interaction ◽  
Spin Splitting ◽  
Large Contribution ◽  
Spin Orbit ◽  
Energy Bands ◽  
Orbit Splitting ◽  
Spin Orbit Interaction ◽  
Nodal Lines ◽  
Nodal Surfaces

It is commonly believed that the energy bands of typical collinear antiferromagnets (AFs), which have zero net magnetization, are Kramers spin-degenerate. Kramers nondegeneracy is usually associated with a global time-reversal symmetry breaking (e.g., via ferromagnetism) or with a combination of spin–orbit interaction and broken spatial inversion symmetry. Recently, another type of spin splitting was demonstrated to emerge in some collinear magnets that are fully spin compensated by symmetry, nonrelativistic, and not even necessarily noncentrosymmetric. These materials feature nonzero spin density staggered in real space as seen in traditional AFs but also spin splitting in momentum space, generally seen only in ferromagnets. This results in a combination of materials characteristics typical of both ferromagnets and AFs. Here, we discuss this recently discovered class with application to a well-known semiconductor, FeSb2, and predict that with certain alloying, it becomes magnetic and metallic and features the aforementioned magnetic dualism. The calculated energy bands split antisymmetrically with respect to spin-degenerate nodal surfaces rather than nodal points, as in the case of spin–orbit splitting. The combination of a large (0.2-eV) spin splitting, compensated net magnetization with metallic ground state, and a specific magnetic easy axis generates a large anomalous Hall conductivity (∼150 S/cm) and a sizable magnetooptical Kerr effect, all deemed to be hallmarks of nonzero net magnetization. We identify a large contribution to the anomalous response originating from the spin–orbit interaction gapped anti-Kramers nodal surfaces, a mechanism distinct from the nodal lines and Weyl points in ferromagnets.

REACTIONS OF DOUBLY CHARGED IONS WITH VARIOUS NEUTRALS

1979 ◽  
Vol 40 (C7) ◽  
pp. C7-21-C7-22
Author(s):  
K. Peska ◽  
E. Alge ◽  
H. Villinger ◽  
H. Störi ◽  
W. Lindinger
Keyword(s):  
Doubly Charged Ions ◽  
Doubly Charged ◽  
Charged Ions

Triatomic molecules

2018 ◽  
Author(s):  
John H. D. Eland ◽  
Raimund Feifel
Keyword(s):  
Degrees Of Freedom ◽  
Normal Modes ◽  
Electronic States ◽  
Triatomic Molecules ◽  
Doubly Charged Ions ◽  
Spectral Bands ◽  
Valence Electrons ◽  
Doubly Charged ◽  
Charged Ions ◽  
Double Ionisation

Double ionisation of the triatomic molecules presented in this chapter shows an added degree of complexity. Besides potentially having many more electrons, they have three vibrational degrees of freedom (three normal modes) instead of the single one in a diatomic molecule. For asymmetric and bent triatomic molecules multiple modes can be excited, so the spectral bands may be congested in all forms of electronic spectra, including double ionisation. Double photoionisation spectra of H2O, H2S, HCN, CO2, N2O, OCS, CS2, BrCN, ICN, HgCl2, NO2, and SO2 are presented with analysis to identify the electronic states of the doubly charged ions. The order of the molecules in this chapter is set first by the number of valence electrons, then by the molecular weight.

scholarly journals Dirac nodal lines protected against spin-orbit interaction in IrO2

2019 ◽  
Vol 3 (6) ◽  
Author(s):  
J. N. Nelson ◽  
J. P. Ruf ◽  
Y. Lee ◽  
C. Zeledon ◽  
J. K. Kawasaki ◽  
...  
Keyword(s):  
Orbit Interaction ◽  
Spin Orbit ◽  
Spin Orbit Interaction ◽  
Nodal Lines

scholarly journals Enhancement of the transverse thermoelectric conductivity originating from stationary points in nodal lines

2020 ◽  
Vol 102 (20) ◽  
Author(s):  
Susumu Minami ◽  
Fumiyuki Ishii ◽  
Motoaki Hirayama ◽  
Takuya Nomoto ◽  
Takashi Koretsune ◽  
...  
Keyword(s):  
Stationary Points ◽  
Nodal Lines

scholarly journals Cobalt-based magnetic Weyl semimetals with high-thermodynamic stabilities

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Wei Luo ◽  
Yuma Nakamura ◽  
Jinseon Park ◽  
Mina Yoon
Keyword(s):  
Tight Binding ◽  
Three Dimensional ◽  
Interlayer Coupling ◽  
First Principles Calculation ◽  
Optimization Approach ◽  
Binding Model ◽  
Nodal Lines ◽  
Weyl Semimetal ◽  
Topological Quantum ◽  
First Time

AbstractRecent experiments identified Co3Sn2S2 as the first magnetic Weyl semimetal (MWSM). Using first-principles calculation with a global optimization approach, we explore the structural stabilities and topological electronic properties of cobalt (Co)-based shandite and alloys, Co3MM’X2 (M/M’ = Ge, Sn, Pb, X = S, Se, Te), and identify stable structures with different Weyl phases. Using a tight-binding model, for the first time, we reveal that the physical origin of the nodal lines of a Co-based shandite structure is the interlayer coupling between Co atoms in different Kagome layers, while the number of Weyl points and their types are mainly governed by the interaction between Co and the metal atoms, Sn, Ge, and Pb. The Co3SnPbS2 alloy exhibits two distinguished topological phases, depending on the relative positions of the Sn and Pb atoms: a three-dimensional quantum anomalous Hall metal, and a MWSM phase with anomalous Hall conductivity (~1290 Ω−1 cm−1) that is larger than that of Co2Sn2S2. Our work reveals the physical mechanism of the origination of Weyl fermions in Co-based shandite structures and proposes topological quantum states with high thermal stability.

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