Magnetic relaxation of superconducting YBCO samples in weak magnetic fields

TL;DR

This study investigates the magnetic relaxation behavior of YBCO superconductors in very weak magnetic fields near critical temperatures, highlighting the impact of twin boundaries and estimating pinning potentials.

Contribution

It presents the first detailed analysis of magnetization relaxation in YBCO samples with various structures under extremely weak magnetic fields near critical temperatures.

Findings

Twin boundaries significantly affect relaxation rates.

Effective pinning potential estimated using collective pinning model.

Magnetization relaxation observed at fields <= 0.1 Oe near critical temperatures.

Abstract

For the first time, magnetization of high-Tc samples with different crystalline structure and its isothermal relaxation is studied at very weak constant fields (H <= 0.1 Oe) for temperatures close to the critical ones. Essential influence of twin boundaries in YBCO single crystals on magnetic relaxation rate is shown. An estimation of effective pinning potential is made in the framework of the collective pinning model.