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