Why is the Tc so high in Fe-based pnictide and chalcogenide superconductors?

Bing Lv, Liangzi Deng, Zheng Wu, Fengyan Wei, Kui Zhao, James K. Meen, Yu Yi Xue, Li Li Wang, Xu Cun Ma, Qi Kun Xue, Ching Wu Chu

Research output: Contribution to journalConference articlepeer-review

4 Citations (Scopus)

Abstract

Recently, the detection of non-bulk superconductivity with unexpectedly high onset-Tcs up to 49 K in Pr-doped CaFe2As2 [(Ca,Pr)122] single crystals and the report of a Tc up to 65 K in one-unit-cell (1UC) FeSe epi-films, offer an unusual opportunity to seek an answer to the question posed in the title. Through systematic compositional, structural, resistive, and magnetic investigations on (Ca,Pr)122 single crystals, we have observed a doping-level-independent Tc, the simultaneous appearance of superparamagnetism and superconductivity, large magnetic anisotropy, and the existence of mesoscopic-2D structures in these crystals, thus providing clear evidence consistent with the proposed interface-enhanced Tc in these naturally occurring rareearth-doped Fe-based superconductors, (Ca,R)122. Similar resistive and magnetic measurements were also made on the 3-4UC FeSe ultrathin epi-films. We have detected weak links in the Meissner state below 20 K, weakly coupled small superconducting patches between 20-45 K, and collective excitations of spin and/or superconducting nature between 45-80 K. The unusual frequency dependences of the diamagnetic moment observed in the films in different temperature ranges will be presented and their implications discussed.

Original languageEnglish
JournalMaterials Research Society Symposium Proceedings
Volume1684
DOIs
Publication statusPublished - 2014
Event2014 MRS Spring Meeting - San Francisco, United States
Duration: 2014 Apr 212014 Apr 25

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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