Neutron Scattering Study of the Intermediate-Valent Ground State in SmB
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Alekseev, P. A.; Lazukov, V. N.; Osborn, R.; Rainford, B.D.; Sadikov, I. P.; Konovalova, E.S.; Paderno, Yu. B.

doi:10.1209/0295-5075/23/5/008

Cited by 46 publications

(42 citation statements)

References 16 publications

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“…These states within the gap can also greatly affect other low energy excitations of SmB 6 . For instance, previous experiments indicate a magnetically active collective spin-exciton which results from the electron-hole continuum to exist within the gap of SmB 6 with an energy of ≈ 14 meV [53][54][55][56] . In a recent neutron scattering study 36,57 , the width of the exciton was observed to be exceptionally narrow, ≈ 2 meV, although more recent measurements with improved resolution suggest the width of the resonance to be even narrower than that, ≈ 100 µeV 58 .…”

Section: Coupling Of Bulk States To Spin Excitonsmentioning

confidence: 99%

Anomalous three-dimensional bulk ac conduction within the Kondo gap of SmB6 single crystals

et al. 2016

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The Kondo insulator SmB6 has long been known to display anomalous transport behavior at low temperatures, T < 5 K. In this temperatures range, a plateau is observed in the dc resistivity, contrary to the exponential divergence expected for a gapped system. Recent theoretical calculations suggest that SmB6 may be the first topological Kondo insulator (TKI) and propose that the residual conductivity is due to topological surface states which reside within the Kondo gap. Since the TKI prediction many experiments have claimed to observe high mobility surface states within a perfectly insulating hybridization gap. Here, we investigate the low energy optical conductivity within the hybridization gap of single crystals of SmB6 via time domain terahertz spectroscopy. Samples grown by both optical floating zone and aluminum flux methods are investigated to probe for differences originating from sample growth techniques. We find that both samples display significant 3D bulk conduction originating within the Kondo gap. Although SmB6 may be a bulk dc insulator, it shows significant bulk ac conduction that is many orders of magnitude larger than any known impurity band conduction. The nature of these in-gap states and their coupling with the low energy spin excitons of SmB6 is discussed. Additionally, the well defined conduction path geometry of our optical experiments allows us to show that any surface states, which lie below our detection threshold if present, must have a sheet resistance of R/ ≥ 1000 Ω.

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Section: Coupling Of Bulk States To Spin Excitonsmentioning

confidence: 99%

Anomalous three-dimensional bulk ac conduction within the Kondo gap of SmB6 single crystals

et al. 2016

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“…It can also be noted that, in Sm 1−x Y x S, the renormalization of the energy of the lower peak as valence increases is not so strong as for the "exciton" peak in Sm 1−x La x B 6 . Whereas for Sm 0.83 Y 0.17 S an optimum fit is achieved using the value of ⌬ ␤ calculated from the empirical relationship derived in hexaborides 3 between the peak energy and the valence, the change in this value required to fit the data for larger concentrations x = 0.25 and 0.33, is not as large as would be expected from the latter relationship.…”

Section: Intermultiplet Transitionsmentioning

confidence: 99%

Magnetic spectral response and lattice properties in mixed-valenceSm1−xYxSsolid solutions studied with x-ray diffraction, x-ray absorption spectroscopy, and inelastic neutron scatte

et al. 2006

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Mixed-valence phenomena occurring in the "black" ͑B͒ and "gold" ͑G͒ phases of Sm 1−x Y x S have been studied by x-ray diffraction, x-ray absorption spectroscopy, and inelastic neutron scattering. Lattice-constant and phonon-dispersion results confirm that the valence instability occurs already inside the B phase. On the other hand, pronounced temperature anomalies in the thermal expansion ␣͑T͒, as well as in the Sm meansquare displacements, denote the onset of the B-G transition for the compositions x = 0.33 and 0.45. It is argued that these anomalies primarily denote an effect of electron-phonon coupling. The magnetic spectral response, measured on both powder and single crystals, is dominated by the Sm 2+ spin-orbit component close to 36 meV. A strongly overdamped Sm 3+ contribution appears only for x Ն 0.33 near room temperature. The quasielastic signal is strongly suppressed below 70 K, reflecting the formation of the singlet mixed-valence ground state. Quite remarkably, the signal around 36 meV is found, from the single-crystal spectra, to arise from two distinct, dispersive, interacting branches. The lower peak, confirmed to exist from x = 0.17 to x = 0.33 at least, is tentatively ascribed to an excitation specific to the mixed-valence regime, reminiscent of the "exciton" peak reported previously for SmB 6 .

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“…Specifically for SmB 6 , a small electronic gap (∆ = 2 − 30 K) was detected by many experimental techniques, e.g. optical conductivity [4], infrared absorption [5,6], inelastic neutron scattering [7], electron tunneling [8][9][10], and electrical transport measurements [10][11][12][13][14][15][16].…”

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confidence: 99%

SmB 6 : Topological insulator or semiconductor with valence-fluctuation induced hopping transport?

Baťko

Baťková

2014

Solid State Communications

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Neutron Scattering Study of the Intermediate-Valent Ground State in SmB ₆

Cited by 46 publications

References 16 publications

Anomalous three-dimensional bulk ac conduction within the Kondo gap of SmB6 single crystals

Anomalous three-dimensional bulk ac conduction within the Kondo gap of SmB6 single crystals

Magnetic spectral response and lattice properties in mixed-valenceSm1−xYxSsolid solutions studied with x-ray diffraction, x-ray absorption spectroscopy, and inelastic neutron scatte

SmB 6 : Topological insulator or semiconductor with valence-fluctuation induced hopping transport?

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Neutron Scattering Study of the Intermediate-Valent Ground State in SmB 6

Cited by 46 publications

References 16 publications

Anomalous three-dimensional bulk ac conduction within the Kondo gap of SmB6 single crystals

Anomalous three-dimensional bulk ac conduction within the Kondo gap of SmB6 single crystals

Magnetic spectral response and lattice properties in mixed-valenceSm1−xYxSsolid solutions studied with x-ray diffraction, x-ray absorption spectroscopy, and inelastic neutron scatte

SmB 6 : Topological insulator or semiconductor with valence-fluctuation induced hopping transport?

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Neutron Scattering Study of the Intermediate-Valent Ground State in SmB ₆