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- Title
Multiple andreev reflections spectroscopy of superconducting LiFeAs single crystals: Anisotropy and temperature behavior of the order parameters.
- Authors
Kuzmichev, S.; Kuzmicheva, T.; Boltalin, A.; Morozov, I.
- Abstract
The superconducting state of LiFeAs single crystals with the maximum critical temperature T ≈ 17 K in the 111 family has been studied in detail by multiple Andreev reflections (MAR) spectroscopy implemented by the break-junction technique. The three superconducting gaps, Δ = 5.1-6.5 meV, Δ = 3.8-4.8 meV, and Δ = 0.9-1.9 meV (at T ≪ T), as well as their temperature dependences, have been directly determined in a tunneling experiment with these samples. The anisotropy degrees of the order parameters in the k space have been estimated as <8, ∼12, and ∼20%, respectively. Andreev spectra have been fitted within the extended Kümmel-Gunsenheimer-Nikolsky model with allowance for anisotropy. The relative electron-boson coupling constants in LiFeAs have been determined by approximating the Δ( T) dependences by the system of the two-band Moskalenko and Suhl equations. It has been shown that the densities of states in bands forming Δ and Δ are approximately the same, intraband pairing dominates in this case, and the interband coupling constants are related as λ ≈ λ ≪ λ, λ.
- Subjects
ANDREEV reflection; SPECTROMETRY; SUPERCONDUCTORS; LITHIUM compounds; SINGLE crystals; BOSONS
- Publication
JETP Letters, 2014, Vol 98, Issue 11, p722
- ISSN
0021-3640
- Publication type
Article
- DOI
10.1134/S0021364013240120