The spatial distributions of large gap-like structure on Fe(Se,Te) single crystals observed by STM/STS

Sugimoto, Akihiro; Sakai, Yuta; Nagasaka, Kouhei; Ekino, Toshikazu

doi:10.1016/j.physc.2015.04.007

Cited by 6 publications

(2 citation statements)

References 17 publications

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“…To determine the gap size more precisely, we fit the tunneling spectrum with the Dynes function. The fitting curve is obtained by the thermal broadened density of states (DOS), which was calculated from the tunneling current expression [38,39]: ab plane, the superconducting gap is suppressed. No vortex state can be found before the gap is closed, in spite of many attempts have been done on various regions of different surfaces and samples.…”

Section: Resultsmentioning

confidence: 99%

Evidence of topological nodal lines and surface states in the centrosymmetric superconductor SnTaS2

Chen,

Liu,

Yang

et al. 2020

Preprint

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The discovery of signatures of topological superconductivity in superconducting bulk materials with topological surface states has attracted intensive research interests recently. Utilizing angle-resolved photoemission spectroscopy and first-principles calculations, here, we demonstrate the existence of topological nodal-line states and drumheadlike surface states in centrosymmetric superconductor SnTaS 2 , which is a type-II superconductor with a critical transition temperature of about 3 K. The valence bands from Ta 5d orbitals and the conduction bands from Sn 5p orbitals cross each other, forming two nodal lines in the vicinity of the Fermi energy without the inclusion of spin-orbit coupling (SOC), protected by the spatial-inversion symmetry and time-reversal symmetry. The nodal lines are gapped out by SOC. The drumheadlike surface states, the typical characteristics in nodal-line semimetals, are quite visible near the Fermi level. Our findings indicate that SnTaS 2 offers a promising platform for exploring the exotic properties of the topological nodal-line fermions and gives a help to study topological superconductivity.

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Section: Resultsmentioning

confidence: 99%

Evidence of topological nodal lines and surface states in the centrosymmetric superconductor SnTaS2

Chen,

Liu,

Yang

et al. 2020

Preprint

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show abstract

“…Such a struggle for the Fermi surface (FS) is quite ubiquitous, e.g. in layered cuprates [18][19][20][21][22][23][24][25] and iron-based superconductors [26][27][28][29][30][31][32][33] with their high critical temperatures, T c 's, and peculiar physical properties, which makes them important research objects. Layered dichalcogenides constitute another testing ground for the studies of the competition between and the coexistence of Cooper pairing and charge density waves (CDWs) [8,15,24,[34][35][36][37][38][39][40][41][42], the latter being the most typical kind of the electron spectrum instability.…”

Section: Introductionmentioning

confidence: 99%

Quasiparticle conductance-voltage characteristics for break junctions involvingd-wave superconductors: charge-density-wave effects

Ekino¹,

Gabovich²,

Li³

et al. 2017

J. Phys.: Condens. Matter

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Quasiparticle tunnel conductance-voltage characteristics (CVCs), [Formula: see text], were calculated for break junctions (BJs) made up of layered d-wave superconductors partially gapped by charge-density waves (CDWs). The current is assumed to flow in the ab-plane of electrodes. The influence of CDWs is analyzed by comparing the resulting CVCs with CVCs calculated for BJs made up of pure d-wave superconductors with relevant parameters. The main CDW-effects were found to be the appearance of new CVC peculiarities and the loss of CVC symmetry with respect to the V-sign. Tunnel directionality was shown to be one of the key factors in the formation of [Formula: see text] dependences. In particular, the orientation of electrodes with respect to the current channel becomes very important. As a result, [Formula: see text] can acquire a large variety of forms similar to those for tunnel junctions between superconductors with s-wave, d-wave, and mixed symmetry of their order parameters. The diversity of peculiarities is especially striking at finite temperatures. In the case of BJs made up of pure d-wave superconductors, the resulting CVC can include a two-peak gap-driven structure. The results were compared with the experimental BJ data for a number of high-T oxides. It was shown that the large variety of the observed current-voltage characteristics can be interpreted in the framework of our approach. Thus, quasiparticle tunnel currents in the ab-plane can be used as an additional mean to detect CDWs competing with superconductivity in cuprates or other layered superconductors.

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Observation of periodic structures and pseudogaps in pristine compound α-TiNCl by STM/STS and break junction methods

Sugimoto

Matsumoto

Saito

et al. 2023

Low Temperature Physics

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Scanning tunneling microscopy and spectroscopy (STM/STS) and break-junction tunnel spectroscopy (B.TTS) measurements are performed on the pristine layered α-TiNCl semiconductor (pri-TiNCl), being the precursor of superconducting nitride chlorides. The STM topography of pri-TiNCl shows basic crystal structures with the lattice periods of a0≈ 0.38 nm and b0≈ 0.31 nm, ensuring that a clean a–b surface of micro-single crystals is obtained. From the STS measurements, the averaged conductance versus voltage dependence dI/dV(V) reveals kink structures at relatively high bias voltages of |F| ∼ −50 mV and −100 mV. The spatial (r-) conductance distributions dI/dV (V, r) (dI/dV maps) proportional to those of quasiparticle local densities of states (LDOSes) exhibit the bias-independent streak structures with the period of (4.8 ± 0.2) b0, which are predominantly observed within the range of |V| < 95 mV. The temperature dependence of the dI/dV B.TTS spectra shows the gap structure with the energy scale of 4Σ = 180 meV vanishing at Ts ∼ 120 K. Thus, the ratio of the gap Σ to the transition temperature Ts is 2Σ/kBTs ∼ 10. Here, kB is the Boltzmann constant. Such a ratio is typical of the pseudogap features in cuprate superconductors and dielectric gap characteristics in layered chalcogenides with charge-density waves.

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The spatial distributions of large gap-like structure on Fe(Se,Te) single crystals observed by STM/STS

Cited by 6 publications

References 17 publications

Evidence of topological nodal lines and surface states in the centrosymmetric superconductor SnTaS2

Evidence of topological nodal lines and surface states in the centrosymmetric superconductor SnTaS2

Quasiparticle conductance-voltage characteristics for break junctions involvingd-wave superconductors: charge-density-wave effects

Observation of periodic structures and pseudogaps in pristine compound α-TiNCl by STM/STS and break junction methods

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