Local density of states and superconducting gap in the iron chalcogenide superconductor Fe1+δSe1−xTex observed by scanning tunneling spectroscopy
Takuya Kato, Yoshikazu Mizuguchi, Hiroshi Nakamura, Tadashi Machida, Hideaki Sakata, Yoshihiko Takano
DOI 10.1103/PhysRevB.80.180507 · Physical Review B
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Abstract
We report on the investigation of the quasiparticle local density of states and superconducting gap in the iron chalcogenide superconductor Fe1+δSe1−xTex(Tc∼14 K). The surface of a cleaved crystal revealed an atomic square lattice, superimposed on the inhomogeneous background, with a lattice constant of ∼3.8 Å without any reconstruction. Tunneling spectra measured at 4.2 K exhibit the superconducting gap, which completely disappears at 18 K, with a magnitude of ∼2.3 meV, corresponding to 2Δ/kBTc=3.8. In stark contrast to the cuprate superconductors, the value of the observed superconducting gap is relatively homogeneous, following a sharp distribution with a small standard deviation of 0.23 meV. Conversely, the normal-state local density of states observed above Tc shows spatial variation over a wide energy range of more than 1 eV, probably due to the excess iron present in the crystal.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| Fe1+δSe1-xTex Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 14 | Pressure not reported | onset |
| Fe1.05Se0.15Te0.85 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 14 | Pressure not reported | onset |
| Fe1+δSe1-xTex Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 18 | Pressure not reported | zero_resistance |
| LaFeAsO1-xFx Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 26 | Pressure not reported | unknown |
| FeSe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 8 | Pressure not reported | unknown |
| FeSe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 37 | Pressure not reported | unknown |
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