TY - JOUR
T1 - Magnetic relaxation and pinning in Ag/Bi(Pb)SCCO tapes
T2 - Deformation-induced effects
AU - Beilin, V.
AU - Goldgirsh, A.
AU - Felner, I.
AU - Schieber, M.
PY - 1997/6
Y1 - 1997/6
N2 - Magnetic hysteresis and magnetic relaxation in as-sintered and cold-pressed after sintering Ag/Bi-2223 tapes have been studied in the temperature range of 5-45 K for two field orientations: H∥c-axis and H∥ab-plane. Significantly higher effective pinning energy, Ueff, for H∥ab as compared to that for H∥c, is connected with the mechanism of intrinsic pinning for the vortex motion normal to the CuO2 atomic planes. Cold pressing results in the reduction of magnetization and transport inter-granular currents due to the introduction of additional weak links and microcracks into a sample. For the H∥c case the drastic drop in relaxation rate as well as the increase in the field of the first large scale vortex penetration, Hvp, was observed after cold pressing, indicating the enhancement of intra-granular and surface pinning by generated defects. Accordingly , the increase of Ueff in the limit of low currents was observed after cold pressing. Warm pressing which normally generates significantly lower concentration of residual defects than cold pressing, does not result in any inhibition of relaxation. For in-plane field H∥ab vortices penetration into a tape interior through microcracks is the dominating deformation-induced effect resulting in the acceleration of magnetic relaxation and the significant decrease of Ueff.
AB - Magnetic hysteresis and magnetic relaxation in as-sintered and cold-pressed after sintering Ag/Bi-2223 tapes have been studied in the temperature range of 5-45 K for two field orientations: H∥c-axis and H∥ab-plane. Significantly higher effective pinning energy, Ueff, for H∥ab as compared to that for H∥c, is connected with the mechanism of intrinsic pinning for the vortex motion normal to the CuO2 atomic planes. Cold pressing results in the reduction of magnetization and transport inter-granular currents due to the introduction of additional weak links and microcracks into a sample. For the H∥c case the drastic drop in relaxation rate as well as the increase in the field of the first large scale vortex penetration, Hvp, was observed after cold pressing, indicating the enhancement of intra-granular and surface pinning by generated defects. Accordingly , the increase of Ueff in the limit of low currents was observed after cold pressing. Warm pressing which normally generates significantly lower concentration of residual defects than cold pressing, does not result in any inhibition of relaxation. For in-plane field H∥ab vortices penetration into a tape interior through microcracks is the dominating deformation-induced effect resulting in the acceleration of magnetic relaxation and the significant decrease of Ueff.
UR - http://www.scopus.com/inward/record.url?scp=0344594637&partnerID=8YFLogxK
U2 - 10.1088/0953-2048/10/6/006
DO - 10.1088/0953-2048/10/6/006
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AN - SCOPUS:0344594637
SN - 0953-2048
VL - 10
SP - 416
EP - 423
JO - Superconductor Science and Technology
JF - Superconductor Science and Technology
IS - 6
ER -