Changing of the excess conductivity near the irreversibility temperature of the top seeded YBa₂Cu₃O₇₋ₓ
Yükleniyor...
Tarih
2024
Yazarlar
Dergi Başlığı
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Yayıncı
Elsevier Ltd
Erişim Hakkı
info:eu-repo/semantics/embargoedAccess
Özet
A top seeded YBa?Cu?O??? (YBCO) superconductor was grown using a bulk Nd123 seed crystal. Orientation peaks directed in the c-axis were observed from the X-ray diffraction measurement for the Y123 sample, indicating single crystal behavior. Magneto-resistivity measurements were carried out as a function of temperature under applied magnetic fields up to 4 T. The superconducting transition temperature (Tc) of the sample was obtained to be approximately 93 K and the excess conductivity curve was obtained experimentally from the resistivity measurement at zero magnetic field. The critical exponents were found to be ?sfw = 2.26 ± 0.25, ?3D = 0.47 ± 0.03 and ?2D = 0.82 ± 0.07 for the short wave fluctuation (SWF) region and the mean field region characterized by 3D and 2D fluctuations, respectively. The crossover temperature determined from the crossover from 2D to 3D regime was found to be 96.37 K. The irreversible temperatures determined from the magneto-resistivity measurements and the irreversibility field line of the sample was obtained using the giant flux creep (gfc) model. The sample exhibits a behavior consistent with the gfc and the vortex glass model according to the n parameter calculated from the resistivity temperature measurements. The width enlarges with the applied magnetic field and was found to be approximately 4 K at 4 T for the Y123 sample. The sample was in the 3D regime below 96.37 K, while the sample was in the 2D regime between 96.37 K and 101.35 K. On the other hand, the reversible region was confined between 93.95 K and 93.33 K at 0 T. It was observed that 3D fluctuations are dominant in the reversible region, whereas 2D fluctuations are dominant in the irreversible region.
Açıklama
Anahtar Kelimeler
Excess Conductivity, Giant Flux Creep Model, Irreversible Temperature, Top Seeded Y123
Kaynak
Journal of Physics and Chemistry of Solids
WoS Q Değeri
Q2
Scopus Q Değeri
Q1
Cilt
193
