TY - JOUR
T1 - The unusually high T c in rare-earth-doped single crystalline CaFe 2As 2
AU - Wei, Fengyan
AU - Lv, Bing
AU - Deng, Liangzi
AU - Meen, James K.
AU - Xue, Yu Yi
AU - Chu, Ching Wu
N1 - Funding Information:
The work in Houston is supported in part by US Air Force Office of Scientific Research [grant number FA9550-09-1-0656]; US Air Force Research Laboratory [Subcontract R15901 (CONTACT)] through Rice University; the T. L. L. Temple Foundation; the John J. and Rebecca Moores Endowment and the State of Texas through the Texas Center for Superconductivity at the University of Houston.
PY - 2014/8/3
Y1 - 2014/8/3
N2 - 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.
AB - 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.
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U2 - 10.1080/14786435.2014.913116
DO - 10.1080/14786435.2014.913116
M3 - Article
AN - SCOPUS:84904395632
SN - 1478-6435
VL - 94
SP - 2562
EP - 2570
JO - Philosophical Magazine
JF - Philosophical Magazine
IS - 22
ER -