LnFeAsO single crystals grown at high pressure: influence of doping and substitutions on superconducting properties and structure
|Janusz Karpinski 1, Nikolai D. Zhigadlo 2, Sergiy Katrych 1, Philip J. Moll 2, K. Rogacki 3, Roman Puzniak 4, Andrea Pisoni 1, Bertram Batlogg 2, Stephen Weyeneth 5, Hugo Keller 5, Laszlo Forro 1|
1. Institute of Condensed Matter Physics EPFL, Ecublens, Lausanne 1015, Switzerland
For the investigations of intrinsic properties relevant for applications of FeAs based superconductors studies on single crystals are necessary. LnFeAsO (Ln=La, Pr, Nd, Sm, Gd) single crystals were grown from flux at high-pressure of 30 kbar. Two kind of fluxes have been used: NaCl/KCl and NaAs/KAs. An overview of the basic superconducting properties measured on single crystals of LnFeAsO will be presented. LnFeAsO compounds show the highest Tc up to 55K and the highest upper critical fields. Superconductivity in LnFeAsO single crystals has been induced by partial substitution of O by F or by H, Sm by Th, Fe by Co, As by P or by oxygen deficiency. Single crystal structure investigations show structure modifications due to substitutions which are linked to superconducting properties. Especially substitution of H for O is important, because it allows much higher doping rate than substitution of F for O. Detailed study of the transport properties of SmFeAs(O,F) single crystals reveals a promising combination of high (> 2 106 A/cm2) and nearly isotropic critical current densities up to 30 T at low temperatures. In the frame of these studies new superconductor related to LnFeAsO, but with much larger c lattice parameter with Tc up to 40K has been discovered. Properties of new superconductor will be presented.
Presentation: Invited oral at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, Topical Session 1, by Janusz Karpinski
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17
Submitted: 2013-04-11 10:43 Revised: 2013-04-11 10:55
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