Magnetism and superconductivity usually do not coexist easily as a superconductor is destroyed by a large magnetic field. However, one of the new iron-based superconductors of the pnictide family has shown both good superconductivity and very strong magnetism. Physicists from the Laboratoire de Physique des Solides in collaboration with german labs from Augsburg and Stuttgart have shown that actually, only a small part of the material is superconducting. The compond consists in an alternated structure of very thin superconducting layers and thick magnetic ones.
For that purpose, they have analized samples from a Rubidium, Selenium and Iron based superconductor using Nuclear Magnetic Resonance. This method allows to analyse the material in its full volume and determine the magnetic environment of the various atoms. The data evidenced the separation between two phases : a superconducting one and an antiferromagnetic one. The measurements also revealed that the superconducting layer is very similar to the other more conventional iron-based superconductors. It is the natural alternated structure which is really unique here and which had fooled physicists up to now. One question remains now : how this material grows naturally in this layered structure which reminds us of the artificial heterostructures usually used in electronics ?
Reference :
NMR in the 245 iron-selenides Rb0.74Fe1.6Se2 : Phase separation between an antiferromagnet and a superconducting Rb0.3Fe2Se2, Y. Texier, J. Deisenhofer, V. Tsurkan, A. Loidl, D. S. Inosov, G. Friemel, J. Bobroff, Phys.Rev.Lett., 108, 237-002 (8 juin 2012)
Contact chercheurs :
Julien Bobroff (julien.bobroff@u-psud.fr)
Yoan Texier (yoan.texier1@u-psud.fr)
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