Upper critical field and coefficient of magnetoresistance in NdBa₂Cu₃O_7?y and NdBa₂Cu_2.9Mn_0.1O_7?y

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• 作者：Ajay Kumar Ghosh ; ^{akg@phys.jdvu.ac.in} ; ^{akgjup@yahoo.com} ; T.A. Jamadar ; A. Roy
• 关键词：Magnetoresistance ; Upper critical field ; Coherence length
• 刊名：Physica C
• 出版年：2012
• 出版时间：14 December, 2012
• 年：2012
• 卷：483
• 期：Complete
• 页码：144-148
• 全文大小：545 K

文摘

We study the magnetotransport properties of NdBa₂Cu₃O_7?y (NBCO) and NdBa₂Cu_2.9Mn_0.1O_7?y (NBCMO) superconductors. The shifting in the transition curves at several magnetic fields has been used to obtain the H-T phase diagram. The upper critical fields, H_c2(0) and coherence lengths, ¦Î of both compounds have been extracted. The coherence length decreases in NBCMO in comparison to that of the NBCO. The change in the coherence length has been attributed mostly to changes in the resistive paths induced by Mn. The coefficients of the magnetoresistance, ¦Â, of both NBCO and NBCMO in the vicinity of the transition region have been extracted using the variation of Ln (¦¤¦Ñ/¦Ñ₀) as a function of Ln (H²), where ¦¤¦Ñ = ¦Ñ(T,H) ? ¦Ñ(T,0) is the change in the resistivity by the applied magnetic field at any temperature, T. ¦Ñ₀ = ¦Ñ (T,0), represents the resistivity at zero magnetic field.