Evidence of a pseudogap driven by competing orders of multi-band origin in the ferromagnetic superconductor Sr0.5Ce0.5FBiS2

Mohammad Aslam, Arpita Paul, Gohil S. Thakur, Sirshendu Gayen, Ritesh Kumar, Avtar Singh, Shekhar Das, Ashok K. Ganguli, Umesh V. Waghmare, Goutam Sheet

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4 Scopus citations

Abstract

From temperature and magnetic field dependent point-contact spectroscopy on the ferromagnetic superconductor Sr0.5Ce0.5FBiS2 (bulk superconducting K) we observe (a) a pseudogap in the normal state that sustains to a remarkably high temperature of 40 K and (b) two-fold enhancement of T c upto 5 K in the point-contact geometry. In addition, Andreev reflection spectroscopy reveals a superconducting gap of 6 meV for certain point-contacts suggesting that the mean field T c of this system could be approximately 40 K, the onset temperature of pseudo-gap. Our results suggest that quantum fluctuations originating from other competing orders in Sr0.5Ce0.5FBiS2 forbid a global phase coherence at high temperatures thereby suppressing T c. Apart from the known ordering to a ferromagnetic state, our first-principles calculations reveal nesting of a multi-band Fermi surface and a significant electron-phonon coupling that could result in charge density wave-like instabilities.

Original languageEnglish (US)
Article number195701
JournalJournal of Physics Condensed Matter
Volume28
Issue number19
DOIs
StatePublished - Apr 19 2016

Keywords

  • BiS based superconductor
  • PCAR spectroscopy
  • pseudo-gap like structure

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