Andreev spectroscopy of FeSe: Evidence for two-gap superconductivity

被引：22

作者：

Ponomarev, Ya. G. ^{[1
]}

Kuzmichev, S. A. ^{[1
]}

Mikheev, M. G. ^{[1
]}

Sudakova, M. V. ^{[1
]}

Tchesnokov, S. N. ^{[1
]}

Shanygina, T. E. ^{[1
]}

Volkova, O. S. ^{[1
]}

Vasiliev, A. N. ^{[1
]}

Wolf, Th. ^{[2
]}

机构：

[1] Moscow MV Lomonosov State Univ, Low Temp Phys & Superconduct Dept, Moscow 119991, Russia

[2] Inst Festkorperphys, Karlsruher Inst Technol, D-76021 Karlsruhe, Germany

来源：

JOURNAL OF EXPERIMENTAL AND THEORETICAL PHYSICS | 2011年 / 113卷 / 03期

关键词：

HIGH-TEMPERATURE SUPERCONDUCTIVITY; ENERGY-GAP STRUCTURE; REFLECTION SPECTROSCOPY; IRON-PNICTIDES; POINT-CONTACT; SINGLE-CRYSTALS; WEAK LINKS; TRANSITION; JUNCTIONS; YBA2CU3O7-X;

D O I：

10.1134/S1063776111080097

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

Current-voltage characteristics (CVCs) of Andreev superconductor-constriction-superconductor (ScS) contacts in polycrystalline samples of FeSe with the critical temperature T (C) = (12 +/- 1) K have been measured using the break-junction technique. In Sharvin-type nanocontacts, two sets of subharmonic gap structures were detected due to multiple Andreev reflections, indicating the existence of two nodeless superconducting gaps Delta (L) = (2.75 +/- 0.3) meV and Delta (S) = (0.8 +/- 0.2) meV. Well-shaped CVCs for stacks of Andreev contacts with up to five contacts were observed due to the layered structure of FeSe (the intrinsic multiple Andreev reflections effect). An additional fine structure in the CVCs of Andreev ScS nanocontacts is attributed to the existence of a Leggett mode. A linear relation between the superconducting gap Delta (L) and the magnetic resonance energy E (magres) a parts per thousand 2 Delta (L) is found to be valid for layered iron pnictides.

引用

页码：459 / 467

页数：9