Cluster Superconductivity in the Magnetoelectric Pb(Fe1/2Sb1/2)O3 Ceramics

V.V. Lagutaa,b, M. Marysko a, V.A. Stephanovichb, I.P. Raevsky c, N.M. Olekhnovich d, A.V. Pushkarev d, Yu.V. Radyush d, S.I. Raevskaya c, R.O. Kuzian e, V. Chlan f and H. Štěpánková f aInstitute of Physics AS CR, Cukrovarnicka 10, 162 53 Prague, Czech Republic bInstitute of Physics, Opole University, Oleska 48, 45-052 Opole, Poland cResearch Institute of Physics and Faculty of Physics, Southern Federal University, Stachki Ave. 194, 344090, Rostov-on-Don, Russia dScientific-Practical Materials Research Centre, NASB, Minsk, Belarus eInstitute for Problems of Materials Science, National Academy of Sciences of Ukraine, Krjijanovskogo 3, 03142 Kyiv, Ukraine fCharles University in Prague, Faculty of Mathematics and Physics, Prague 1, Czech Republic

Received: November 29, 2016; In final form: April 4, 2017

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We report the observation of cluster (local) superconductivity in the magnetoelectric Pb(Fe1/2Sb1/2)O3 ceramics prepared at a hydrostatic pressure of 6 GPa and temperatures 1200-1800 K to stabilize the perovskite phase. The superconductivity is manifested by an abrupt drop of the magnetic susceptibility at the critical temperature Tc ≈7 K. Both the magnitude of this drop and Tc decrease with magnetic field increase. Similarly, the low-field paramagnetic absorption measured by EPR spectrometer drops significantly below Tc as well. The observed effects and their critical magnetic field dependence are interpreted as manifestation of the superconductivity and the Meissner effect in metallic Pb nanoclusters existing in the ceramics. Their volume fraction and average size were estimated as 0.1-0.2% and 140-150 nm, respectively. The superconductivity related effects disappear after oxidizing annealing of the ceramics.

DOI: 10.12693/APhysPolA.131.1534 PACS/topics: Multiferroics, Superconductivity, magnetic susceptibility