Evidence of a pseudogap driven by competing orders of multi-band origin in the ferromagnetic superconductor Sr0.5Ce0.5FBiS2. (19th April 2016)

• Record Type: Journal Article
• Authors: Aslam, Mohammad; Paul, Arpita; Thakur, Gohil S; Gayen, Sirshendu; Kumar, Ritesh; Singh, Avtar; Das, Shekhar; Ganguli, Ashok K; Waghmare, Umesh V; Sheet, Goutam
• Is Part Of: Journal of physics. Volume 28:Number 19(2016)
• Publication Date: 2016-04-19
• Subjects: BiS2 based superconductor -- pseudo-gap like structure -- PCAR spectroscopy; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/0953-8984/28/19/195701
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: From temperature and magnetic field dependent point-contact spectroscopy on the ferromagnetic superconductor Sr0.5 Ce0.5 FBiS2 (bulk superconducting T c = 2.5 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 Sr0.5 Ce0.5 FBiS2 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.