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Two distinct superconducting phases in LiFeAs.

ABSTRACT: A non-trivial temperature evolution of superconductivity including a temperature-induced phase transition between two superconducting phases or even a time-reversal symmetry breaking order parameter is in principle expected in multiband superconductors such as iron-pnictides. Here we present scanning tunnelling spectroscopy data of LiFeAs which reveal two distinct superconducting phases: at =?18?K a partial superconducting gap opens, evidenced by subtle, yet clear features in the tunnelling spectra, i.e. particle-hole symmetric coherence peak and dip-hump structures. At Tc?=?16?K, these features substantiate dramatically and become characteristic of full superconductivity. Remarkably, the distance between the dip-hump structures and the coherence peaks remains practically constant in the whole temperature regimeT?? . This rules out the connection of the dip-hump structures to an antiferromagnetic spin resonance.

SUBMITTER: Nag PK 

PROVIDER: S-EPMC4906386 | biostudies-other | 2016

REPOSITORIES: biostudies-other

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Two distinct superconducting phases in LiFeAs.

Nag P K PK   Schlegel R R   Baumann D D   Grafe H-J HJ   Beck R R   Wurmehl S S   Büchner B B   Hess C C  

Scientific reports 20160614

A non-trivial temperature evolution of superconductivity including a temperature-induced phase transition between two superconducting phases or even a time-reversal symmetry breaking order parameter is in principle expected in multiband superconductors such as iron-pnictides. Here we present scanning tunnelling spectroscopy data of LiFeAs which reveal two distinct superconducting phases: at = 18 K a partial superconducting gap opens, evidenced by subtle, yet clear features in the tunnelling spec  ...[more]