TY - JOUR
T1 - Magnetic measurements in NdBa2Cu3O7-δ single crystals
T2 - Magnetization, flux pinning and creep
AU - Koblischka, M. R.
AU - Higuchi, T.
AU - Yoo, S. I.
AU - Murakami, M.
AU - Frello, T.
AU - Baziljevich, M.
AU - Johansen, T. H.
AU - Wolf, T.
AU - Diko, P.
N1 - Funding Information:
This work was partially supported by the New Energy and Industrial Technology Development Organization (NEDO) for the R & D of Industrial Science and Technology Frontier Program. The work carried out in Oslo is supported by The Norwegian Research Council. We thank K. Sawada for the preparation of the NdBCO single crystal. M. K. gratefully acknowledges the support from the Japanese Science and Technology Agency (STA).
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 1998
Y1 - 1998
N2 - In this paper, we present the results of various magnetic measurements on an NdBa2Cu3O7-δ (NdBCO) single crystal. Special features observed in the magnetization loops (MHLs) are discussed. From these loops, critical current densities, jc as a function of the applied field, Ha, and volume pinning forces, Fp =jc × B, are derived. The samples exhibit a strong fishtail or peak effect at temperatures above 30 K. In a small temperature window between 50 K and 74 K, even three peaks are seen in the jc(T,Ha) curves. A good scaling of the jc (T,Ha) curves is obtained, which allows the identification of the peaks. The scaled volume pinning forces (vs the reduced field, h = Ha/Hiir), in the temperature regime between 60 and 90 K give experimental evidence for a strong pinning at extended superconducting defects (interaction volume Vpin ∼ξ2d). These defects are ascribed to spatial composition fluctuations found in light rare earth superconductors, providing a scatter of the transition temperature, Tc. Furthermore, the scaling analysis of Fp is extended towards low temperatures. It is shown that at 5 K another peak in Fp is found, which is due to pinning at twin boundaries. Using this scaling analysis of both jc and Fp, the irreversibility line (IL) is determined in the entire temperature range 0-92 K. Magneto-optic (MO) imaging is employed to investigate the flux distributions of various NdBCO single crystals. These images confirm the important role of twin boundaries as pinning sites at low temperatures and low applied fields.
AB - In this paper, we present the results of various magnetic measurements on an NdBa2Cu3O7-δ (NdBCO) single crystal. Special features observed in the magnetization loops (MHLs) are discussed. From these loops, critical current densities, jc as a function of the applied field, Ha, and volume pinning forces, Fp =jc × B, are derived. The samples exhibit a strong fishtail or peak effect at temperatures above 30 K. In a small temperature window between 50 K and 74 K, even three peaks are seen in the jc(T,Ha) curves. A good scaling of the jc (T,Ha) curves is obtained, which allows the identification of the peaks. The scaled volume pinning forces (vs the reduced field, h = Ha/Hiir), in the temperature regime between 60 and 90 K give experimental evidence for a strong pinning at extended superconducting defects (interaction volume Vpin ∼ξ2d). These defects are ascribed to spatial composition fluctuations found in light rare earth superconductors, providing a scatter of the transition temperature, Tc. Furthermore, the scaling analysis of Fp is extended towards low temperatures. It is shown that at 5 K another peak in Fp is found, which is due to pinning at twin boundaries. Using this scaling analysis of both jc and Fp, the irreversibility line (IL) is determined in the entire temperature range 0-92 K. Magneto-optic (MO) imaging is employed to investigate the flux distributions of various NdBCO single crystals. These images confirm the important role of twin boundaries as pinning sites at low temperatures and low applied fields.
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U2 - 10.1016/S0964-1807(98)00105-7
DO - 10.1016/S0964-1807(98)00105-7
M3 - Article
AN - SCOPUS:0031988424
VL - 6
SP - 225
EP - 234
JO - Applied Superconductivity
JF - Applied Superconductivity
SN - 0964-1807
IS - 2-5
ER -