کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1820442 | 1525785 | 2006 | 4 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Three-dimensional and two-dimensional high field vortex fluctuations in deoxygenated YBa2Cu3O7âx depending on the vicinity of Tc(H)
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موضوعات مرتبط
مهندسی و علوم پایه
فیزیک و نجوم
فیزیک ماده چگال
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
We analyzed reversible magnetization data, M versus T curves, of three single crystals of YBa2Cu3O7âx (Y123), with superconducting transition temperatures Tc = 62.5 (x = 0.35), 52 (x = 0.5), and 41 K (x = 0.6). M versus T curves of each sample exhibited a field independent crossing point, M(Tâ), occurring close to the superconductor critical temperature. These crossing points were shown to be due to fluctuations of vortices. Besides the reversible data of each sample were shown to obey a two-dimensional diamagnetic lowest-Landau-level (LLL) fluctuation theory, it is shown here that the data, within a temperature region where the crossing points occur for two samples (62.5 K and 52 K), are also explained by a three-dimensional version of this fluctuation theory. Since the crossing points for these two samples occur close to Tc, these are interpreted as been due to three-dimensional vortex fluctuations instead two-dimensional ones. An expression for the field independent magnetization, M(Tâ), which is expected to occur at the crossing point of the various M versus T curves, is obtained for the case of three-dimensional vortex fluctuations, and compared to the experimental values of M(Tâ). This comparison produced consistent values for the coherence length along the c-axis of the samples with Tc = 62.5 and 52 K, solving an inconsistent result previously published, when experimental values of M(Tâ) were compared with an expression obtained from two-dimensional vortex-fluctuations. The results of the present work show that, despite the fact that two-dimensional LLL fluctuations scaling is obeyed in a much wider temperature range for two studied samples (Tc = 52 (x = 0.5), and 62.5 K (x = 0.35)) when compared to the 3D-LLL scaling form, these systems behave as three-dimensional for temperatures close to Tc(H).
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Physica C: Superconductivity - Volume 443, Issues 1â2, 1 September 2006, Pages 1-4
Journal: Physica C: Superconductivity - Volume 443, Issues 1â2, 1 September 2006, Pages 1-4
نویسندگان
S. Jr., E.Z. da Silva, A.D. Alvarenga,