The unusually high T c in rare-earth-doped single crystalline CaFe 2As 2

Fengyan Wei, Bing Lv, Liangzi Deng, James K. Meen, Yu Yi Xue, Ching Wu Chu

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


In rare-earth-doped single crystalline CaFe2As2, the mysterious small volume fraction which superconducts up to 49 K, much higher than the bulk Tc ~ 30 s K, has prompted a long search for a hidden variable that could enhance the Tc by more than 30% in iron-based superconductors of the same structure. Here we report a chemical, structural and magnetic study of CaFe2As2 systematically doped with La, Ce, Pr and Nd. Coincident with the high Tc phase, we find extreme magnetic anisotropy, accompanied by an unexpected doping-independent T c and equally unexpected superparamagnetic clusters associated with As vacancies. These observations lead us to conjecture that the tantalizing Tc enhancement may be associated with naturally occurring chemical interfaces and may thus provide a new paradigm in the search for superconductors with higher Tc.

Original languageEnglish
Pages (from-to)2562-2570
Number of pages9
JournalPhilosophical Magazine
Issue number22
Publication statusPublished - 2014 Aug 3

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics


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