Spin-excitons in heavy-fermion semimetals

Riseborough, Peter S.; Magalhães, S. G.

doi:10.1016/j.jmmm.2015.07.043

Cited by 5 publications

(2 citation statements)

References 28 publications

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“…These materials are enabled by broken spatial or time inversion symmetries, and the large spin orbit interactions which collapses the conduction and valence bands within a limited section of the Brillouin zone where the conduction and valence bands cross and invert. Dirac, Weyl, nodal-line, and nested fermion semimetals have all been predicted theoretically and observed experimentally 6 – 11 . Weyl semimetals are particularly interesting since pairs of Weyl nodes with opposite chirality appear as monopole sources and sinks of Berry curvature 12 , 13 .…”

Section: Introductionmentioning

confidence: 90%

A Raman probe of phonons and electron–phonon interactions in the Weyl semimetal NbIrTe4

Shojaei

Pournia

et al. 2021

Sci Rep

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There is tremendous interest in measuring the strong electron–phonon interactions seen in topological Weyl semimetals. The semimetal NbIrTe4 has been proposed to be a Type-II Weyl semimetal with 8 pairs of opposite Chirality Weyl nodes which are very close to the Fermi energy. We show using polarized angular-resolved micro-Raman scattering at two excitation energies that we can extract the phonon mode dependence of the Raman tensor elements from the shape of the scattering efficiency versus angle. This van der Waals semimetal with broken inversion symmetry and 24 atoms per unit cell has 69 possible phonon modes of which we measure 19 modes with frequencies and symmetries consistent with Density Functional Theory calculations. We show that these tensor elements vary substantially in a small energy range which reflects a strong variation of the electron–phonon coupling for these modes.

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Section: Introductionmentioning

confidence: 90%

A Raman probe of phonons and electron–phonon interactions in the Weyl semimetal NbIrTe4

Shojaei

Pournia

et al. 2021

Sci Rep

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“…Supporting evidence for the exceptionally long lifetime of the spin-exciton has been provided by recent Raman scattering experiments [36] which see a q ∼ 0 feature at 16 meV with a width of 0.5 meV in an Al flux-grown SmB 6 sample at T = 15 K. The narrow line-width of the spin-exciton is caused by the absence of an electron-hole pair decay channel within the bulk hybridization gap. A shift of the peak from 13 meV in the bulk to 9 meV at the surface would indicate that the surface states are close to a quantum critical point [37]. The existence of large-amplitude, low-frequency spin-flip scattering at the surface would also result in the surface states not being completely protected from back-scattering and gives rise to a resonant peak in the low-temperature surface electronic density of states.…”

Section: Introductionmentioning

confidence: 99%

Effects of spin excitons on the surface states of SmB6 : A photoemission study

et al. 2016

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We present the results of high-resolution valence-band photoemission spectroscopic study of SmB6 which shows evidence for a V-shaped density of states of surface origin within the bulk gap. The spectroscopy data is interpreted in terms of the existence of heavy 4f surface states, which may be useful in resolving the controversy concerning the disparate surface Fermi-surface velocities observed in experiments. Most importantly, we 1 find that the temperature dependence of the valence-band spectrum indicates that a small feature appears at a binding energy of about -9 meV at low temperatures. We attribute this feature to a resonance caused by the spin-exciton scattering in SmB6 which destroys the protection of surface states due to time-reversal invariance and spin-momentum locking. The existence of a low-energy spin-exciton may be responsible for the scattering which suppresses the formation of coherent surface quasi-particles and the appearance of the saturation of the resistivity to temperatures much lower than the coherence temperature associated with the opening of the bulk gap.

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Spin-excitons in high magnetic fields

Yuan

Riseborough

2023

Journal of Magnetism and Magnetic Materials

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Spin-excitons in heavy-fermion semimetals

Cited by 5 publications

References 28 publications

A Raman probe of phonons and electron–phonon interactions in the Weyl semimetal NbIrTe4

A Raman probe of phonons and electron–phonon interactions in the Weyl semimetal NbIrTe4

Effects of spin excitons on the surface states of SmB6 : A photoemission study

Spin-excitons in high magnetic fields

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