Cluster superconductivity in the magnetoelectric Pb(Fe1/2Sb1/2)O3 ceramics

TL;DR

This study reports the discovery of cluster superconductivity in Pb(Fe1/2Sb1/2)O3 ceramics, attributed to metallic Pb nanoclusters, with a critical temperature of 7 K and effects that vanish after oxidation.

Contribution

First observation of cluster superconductivity in magnetoelectric ceramics, linking superconductivity to metallic Pb nanoclusters within the material.

Findings

Superconductivity appears at 7 K in the ceramics.

Superconductivity is linked to Pb nanoclusters of 140-150 nm.

Superconducting effects disappear after oxidation annealing.

Abstract

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 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.