TY - JOUR
T1 - Point-contact Andreev-reflection spectroscopy in Fe(Te,Se) films
T2 - Multiband superconductivity and electron-boson coupling
AU - Daghero, D.
AU - Pecchio, P.
AU - Ummarino, G. A.
AU - Nabeshima, F.
AU - Imai, Y.
AU - Maeda, A.
AU - Tsukada, I.
AU - Komiya, S.
AU - Gonnelli, R. S.
N1 - Publisher Copyright:
© 2014 IOP Publishing Ltd.
PY - 2014/12/1
Y1 - 2014/12/1
N2 - We report on a study of the superconducting order parameter in Fe(Te1?xSex) thin films (with different Se contents: x = 0.3, 0.4, 0.5) by means of point-contact Andreev-reflection spectroscopy (PCARS). The PCARS spectra show reproducible evidence of multiple structures, namely two clear conductance maxima associated to a superconducting gap of amplitude δE ≃ 2.75kBTc and additional shoulders at higher energy that, as we show, are the signature of the strong interaction of charge carriers with a bosonic mode whose characteristic energy coincides with the spin-resonance energy. The details of some PCARS spectra at low energy suggest the presence of a smaller and not easily discernible gap of amplitude δH simel 1.75kBTc. The existence of this gap and its amplitude are confirmed by PCARS measurements in ? Fe(Te1-xSex) single crystals. The values of the two gaps δE and δH, once plotted as a function of the local critical temperature TcA , turn out to be in perfect agreement with the results obtained by various experimental techniques reported in literature.
AB - We report on a study of the superconducting order parameter in Fe(Te1?xSex) thin films (with different Se contents: x = 0.3, 0.4, 0.5) by means of point-contact Andreev-reflection spectroscopy (PCARS). The PCARS spectra show reproducible evidence of multiple structures, namely two clear conductance maxima associated to a superconducting gap of amplitude δE ≃ 2.75kBTc and additional shoulders at higher energy that, as we show, are the signature of the strong interaction of charge carriers with a bosonic mode whose characteristic energy coincides with the spin-resonance energy. The details of some PCARS spectra at low energy suggest the presence of a smaller and not easily discernible gap of amplitude δH simel 1.75kBTc. The existence of this gap and its amplitude are confirmed by PCARS measurements in ? Fe(Te1-xSex) single crystals. The values of the two gaps δE and δH, once plotted as a function of the local critical temperature TcA , turn out to be in perfect agreement with the results obtained by various experimental techniques reported in literature.
KW - Andreev reflection spectroscopy
KW - chalcogenide superconductors
KW - superconducting films
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U2 - 10.1088/0953-2048/27/12/124014
DO - 10.1088/0953-2048/27/12/124014
M3 - Article
AN - SCOPUS:84912017622
SN - 0953-2048
VL - 27
JO - Superconductor Science and Technology
JF - Superconductor Science and Technology
IS - 12
M1 - 124014
ER -