Enhanced pinning in high-temperature superconducting cuprate single crystals at low DC magnetic field

TL;DR

This study investigates flux pinning in NdBa2Cu3O7-x high-temperature superconducting single crystals under low magnetic fields, revealing enhanced pinning potentials and effects of calcium doping near the critical temperature.

Contribution

It presents the first detailed analysis of flux dynamics at low magnetic fields in Nd-based cuprates and demonstrates increased pinning potential due to calcium doping.

Findings

Significant increase in effective pinning potential compared to high-field measurements.

Calcium doping enhances pinning potential with minimal impact on Tc.

Flux relaxation behavior consistent with Anderson-Kim model.

Abstract

Low density flux dynamics in Nd based cuprate (NdBa2Cu3O7-x) HTSC single crystals trapped in 1 Oe range DC magnetic fields were investigated for the first time. Complex measurements of time, temperature and field dependence of magnetization were performed. Using the results obtained and the Anderson-Kim model the normalized magnetization relaxation rate S and the averaged effective pinning potential U were calculated. We show a significant (one or even two orders) increase in the effective pinning potential in these samples in comparison with measurements performed in high magnetic fields for similar cuprate single crystals formerly. In a wide enough range of temperatures close to Tc (0.72 < T/Tc < 0.93) it has been shown that the doping of NdBa2Cu3O7-x single crystals with calcium atoms leads to the increase of the averaged effective pinning potential with an insignificant decreasing of the critical temperature.