Investigation of the Energy Gap in Sm1−xB6and Sm1−xLaxB6Kondo Insulators

Pristáš, G.; Gabáni, S.; Flachbart, К.; Filipov, V. B.; Shitsevalova, N. Yu.

doi:10.7566/jpscp.3.012021

Cited by 5 publications

(5 citation statements)

References 12 publications

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“…In the microfabricated sample (S6), the magnitude of the resistivity plateau was found to be significantly smaller than the macroscopic samples which likely originates from a parallel conduction channel formed in the FIB processing [24]. In general, the variation in IRR values reflects different levels of disorder or off-stoichiometry [25]. In sample S3, the low-temperature plateau in the resistivity exists down to 0.4 K.…”

Section: Resultsmentioning

confidence: 99%

Bulk and in-gap states in SmB6 revealed by high-field magnetotransport

Shahrokhvand¹,

Pezzini²,

Delft³

et al. 2017

Phys. Rev. B

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We report on temperature-dependent magnetotransport experiments of SmB 6 single crystals in high magnetic fields up to 33 T. Above the low-temperature plateau region in the zero-field resistivity, we find two distinct gapped regimes. The first is characterized by a temperature-independent gap 2 that closes in the presence of a high magnetic field while the second regime, above ∼8 K, features an energy gap 1 that is temperature dependent. In the entire temperature range, we observe an overall negative magnetoresistance that does not depend on the orientation of the crystalline plane with respect to the applied magnetic field with a maximum value at T ∼ 6.2 K. The regime of in-gap states is characterized by a low mobility, an anomalously high carrier concentration, and an enhanced nonlocal resistance that exceeds the expected classical value for a two-dimensional metallic conductor. Overall, our data can be interpreted in terms of a transition from bulk to in-gap dominated transport, but evidence of topological surface states is not observed.

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Section: Resultsmentioning

confidence: 99%

Bulk and in-gap states in SmB6 revealed by high-field magnetotransport

Shahrokhvand¹,

Pezzini²,

Delft³

et al. 2017

Phys. Rev. B

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“…Single crystals of SmB 6 used in the present study were grown by means of the image furnace technique [19] in order to achieve high purities as characterised by the high inverse residual resistivity ratio. Single crystals with inverse resistance ratios [IRR = R(T = 1.8 K)/R(T = 300 K), where R is resistance and T is temperature] of the order of 10 5 were selected for this study; the IRR has been shown to characterise crystal quality, with the introduction of point defects by radiation damage [20], or through off-stoichiometry [21] resulting in a decrease in low temperature resistance and an increase in high temperature resistance. The resistance of a SmB 6 single crystal is shown in Fig.…”

mentioning

confidence: 99%

Unconventional Fermi surface in an insulating state

Tan

Hsu

Zeng

et al. 2015

Science

295

366

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Insulators occur in more than one guise, a recent finding was a class of topological insulators, which host a conducting surface juxtaposed with an insulating bulk. Here we report the observation of an unusual insulating state with an electrically insulating bulk that simultaneously yields bulk quantum oscillations with characteristics of an unconventional Fermi liquid. We present quantum oscillation measurements of magnetic torque in high purity single crystals of the Kondo insulator SmB 6 , which reveal quantum oscillation frequencies characteristic of a large three-dimensional conduction electron Fermi surface similar to the metallic rare earth hexaborides such as PrB 6 and LaB 6 . The quantum oscillation amplitude strongly increases at low temperatures, appearing strikingly at variance with conventional metallic behaviour.Kondo insulators, a class of materials positioned close to the border between insulating and metallic behaviour, provide fertile ground for unusual physics [1,2,3,4,5,6,7,8,9,10,11,12,13,14]. This class of strongly correlated materials is thought to be characterised by a 1 arXiv:1507.01129v1 [cond-mat.str-el] 4 Jul 2015

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“…2(a) compares the resistivity as a function of temperature of the floating zone-grown single crystal SmB 6 used for our quantum oscillation measurements, the isotopic floating zone-grown crystal of ref. [12], and crystals grown by various other techniques [24,25,26]. We find that single crystals grown by the floating-zone method exhibit the largest values of iRRR.…”

Section: Laliberte Et Almentioning

confidence: 83%

“…Electrical resistivity as a function of temperature on single crystals of SmB 6 grown by different methods, normalised to the resistivity at 300 K. The inverse residual resistivity of floating zone-grown single crystals of SmB 6 used to measure quantum oscillations in this study reach a value of the order 10 5 , higher than the isotopic floating zone-grown sample with minimal rare-earth impurities from ref. [12], and more than an order of magnitude higher than samples grown by other growth methods (flux [24], induction melting [25], layer evaporation [26]).…”

Section: Laliberte Et Almentioning

confidence: 87%

Intrinsic Bulk Quantum Oscillations in a Bulk Unconventional Insulator SmB6

et al. 2020

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Summary The finding of bulk quantum oscillations in the Kondo insulator SmB 6 proved a considerable surprise. Subsequent measurements of bulk quantum oscillations in other correlated insulators including YbB 12 lent support to our discovery of a class of bulk unconventional insulators that host bulk quantum oscillations. Here we perform a series of experiments to examine evidence for the intrinsic character of bulk quantum oscillations in floating zone-grown single crystals of SmB 6 that have been the subject of our quantum oscillation studies. We present results of thermodynamic, transport, and composition analysis experiments on pristine floating zone-grown single crystals of SmB 6 and compare quantum oscillations with metallic LaB 6 and elemental aluminum. These results establish the intrinsic origin of quantum oscillations from the insulating bulk of floating zone-grown SmB 6 . The similarity of the Fermi surface in insulating SmB 6 with the conduction-electron Fermi surface in metallic hexaborides is at the heart of a theoretical mystery.

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Investigation of the Energy Gap in Sm₁₋_xB₆and Sm₁₋_xLa_xB₆Kondo Insulators

Cited by 5 publications

References 12 publications

Bulk and in-gap states in SmB6 revealed by high-field magnetotransport

Bulk and in-gap states in SmB6 revealed by high-field magnetotransport

Unconventional Fermi surface in an insulating state

Intrinsic Bulk Quantum Oscillations in a Bulk Unconventional Insulator SmB6

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