Effect of Ge4+ and Mg2+ doping on superconductivity, fluctuation induced conductivity and interplanar coupling of TlSr 2CaCu2O7-δ superconductors

A. Ali Yusuf, A. K. Yahya, Nawazish A. Khan, F. Md Salleh, Elya Sufliza Marsom @ Abdul Razak, N. Huda

Research output: Contribution to journalArticle

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Abstract

Substitution of Ge4+ in place of Cu in Tl0.85Cr 0.15Sr2CaCu2-xGexO 7-δ (x = 0-0.6) showed initial increase in zero critical temperature value, Tc zero from 98 K (x = 0) to 100 K (x = 0.1) and in the range of 85-86 K for x = 0.2-0.3. The slow decrease in Tc zero is unexpected as tetravalent Ge4+ substitution is expected to strongly reduce hole concentration in the samples and suppress Tc zero. Excess conductivity analyses of resistance versus temperature data based on Asmalazov-Larkin (AL) theory revealed that the substitution induced 2D-to-3D transition of fluctuation induced conductivity with the highest transition temperature, T 2D-3D observed at x = 0.1. FTIR spectroscopy analysis indicates Ge4+ substitution cause reduction in CuO 2/GeO2 interplanar distance while our calculation based on Lawrence-Doniach model revealed highest superconducting coherence length, ξc(0) and interplanar coupling, J at x = 0.3. On the other hand, substitution of divalent Mg2+ for Ca2+ in (Tl 0.5Pb0.5)(Sr1.8Yb0.2)(Ca 1-yMgy)Cu2O7 (y = 0-1.0), which is not expected to directly vary hole concentration, surprisingly caused Tc zero to increase from 89.6 K (y = 0) to an optimum value of 95.9 K (y = 0.6) before decreasing with further increase in y. Excess conductivity analyses showed 2D-to-3D transition of fluctuation induced conductivity for all samples where the highest T2D- 3D was at y = 0.4. Similar calculation revealed highest values of ξc(0) and J also at y = 0.4. FTIR analysis of the samples indicates inequivalent Cu(1)O(2)Pb/Tl lengths and possible tilting of CuO 2 plane as a result of Mg2+ substitution. The increased ξc(0) and J as a result of the Ge4+ and Mg2+ substitutions are suggested to contributed to sustenance of superconductivity above 80 K in the samples.

Original languageEnglish
Pages (from-to)363-372
Number of pages10
JournalPhysica C: Superconductivity and its Applications
Volume471
Issue number11-12
DOIs
Publication statusPublished - 01 Jun 2011

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Superconductivity
Superconducting materials
Substitution reactions
superconductivity
Doping (additives)
substitutes
conductivity
Hole concentration
Superconducting transition temperature
critical temperature
transition temperature
Spectroscopy
Temperature
causes
spectroscopy

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

Cite this

@article{da524a8f334549828babc337d7b067a1,
title = "Effect of Ge4+ and Mg2+ doping on superconductivity, fluctuation induced conductivity and interplanar coupling of TlSr 2CaCu2O7-δ superconductors",
abstract = "Substitution of Ge4+ in place of Cu in Tl0.85Cr 0.15Sr2CaCu2-xGexO 7-δ (x = 0-0.6) showed initial increase in zero critical temperature value, Tc zero from 98 K (x = 0) to 100 K (x = 0.1) and in the range of 85-86 K for x = 0.2-0.3. The slow decrease in Tc zero is unexpected as tetravalent Ge4+ substitution is expected to strongly reduce hole concentration in the samples and suppress Tc zero. Excess conductivity analyses of resistance versus temperature data based on Asmalazov-Larkin (AL) theory revealed that the substitution induced 2D-to-3D transition of fluctuation induced conductivity with the highest transition temperature, T 2D-3D observed at x = 0.1. FTIR spectroscopy analysis indicates Ge4+ substitution cause reduction in CuO 2/GeO2 interplanar distance while our calculation based on Lawrence-Doniach model revealed highest superconducting coherence length, ξc(0) and interplanar coupling, J at x = 0.3. On the other hand, substitution of divalent Mg2+ for Ca2+ in (Tl 0.5Pb0.5)(Sr1.8Yb0.2)(Ca 1-yMgy)Cu2O7 (y = 0-1.0), which is not expected to directly vary hole concentration, surprisingly caused Tc zero to increase from 89.6 K (y = 0) to an optimum value of 95.9 K (y = 0.6) before decreasing with further increase in y. Excess conductivity analyses showed 2D-to-3D transition of fluctuation induced conductivity for all samples where the highest T2D- 3D was at y = 0.4. Similar calculation revealed highest values of ξc(0) and J also at y = 0.4. FTIR analysis of the samples indicates inequivalent Cu(1)O(2)Pb/Tl lengths and possible tilting of CuO 2 plane as a result of Mg2+ substitution. The increased ξc(0) and J as a result of the Ge4+ and Mg2+ substitutions are suggested to contributed to sustenance of superconductivity above 80 K in the samples.",
author = "{Ali Yusuf}, A. and Yahya, {A. K.} and Khan, {Nawazish A.} and Salleh, {F. Md} and {Marsom @ Abdul Razak}, {Elya Sufliza} and N. Huda",
year = "2011",
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language = "English",
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Effect of Ge4+ and Mg2+ doping on superconductivity, fluctuation induced conductivity and interplanar coupling of TlSr 2CaCu2O7-δ superconductors. / Ali Yusuf, A.; Yahya, A. K.; Khan, Nawazish A.; Salleh, F. Md; Marsom @ Abdul Razak, Elya Sufliza; Huda, N.

In: Physica C: Superconductivity and its Applications, Vol. 471, No. 11-12, 01.06.2011, p. 363-372.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Effect of Ge4+ and Mg2+ doping on superconductivity, fluctuation induced conductivity and interplanar coupling of TlSr 2CaCu2O7-δ superconductors

AU - Ali Yusuf, A.

AU - Yahya, A. K.

AU - Khan, Nawazish A.

AU - Salleh, F. Md

AU - Marsom @ Abdul Razak, Elya Sufliza

AU - Huda, N.

PY - 2011/6/1

Y1 - 2011/6/1

N2 - Substitution of Ge4+ in place of Cu in Tl0.85Cr 0.15Sr2CaCu2-xGexO 7-δ (x = 0-0.6) showed initial increase in zero critical temperature value, Tc zero from 98 K (x = 0) to 100 K (x = 0.1) and in the range of 85-86 K for x = 0.2-0.3. The slow decrease in Tc zero is unexpected as tetravalent Ge4+ substitution is expected to strongly reduce hole concentration in the samples and suppress Tc zero. Excess conductivity analyses of resistance versus temperature data based on Asmalazov-Larkin (AL) theory revealed that the substitution induced 2D-to-3D transition of fluctuation induced conductivity with the highest transition temperature, T 2D-3D observed at x = 0.1. FTIR spectroscopy analysis indicates Ge4+ substitution cause reduction in CuO 2/GeO2 interplanar distance while our calculation based on Lawrence-Doniach model revealed highest superconducting coherence length, ξc(0) and interplanar coupling, J at x = 0.3. On the other hand, substitution of divalent Mg2+ for Ca2+ in (Tl 0.5Pb0.5)(Sr1.8Yb0.2)(Ca 1-yMgy)Cu2O7 (y = 0-1.0), which is not expected to directly vary hole concentration, surprisingly caused Tc zero to increase from 89.6 K (y = 0) to an optimum value of 95.9 K (y = 0.6) before decreasing with further increase in y. Excess conductivity analyses showed 2D-to-3D transition of fluctuation induced conductivity for all samples where the highest T2D- 3D was at y = 0.4. Similar calculation revealed highest values of ξc(0) and J also at y = 0.4. FTIR analysis of the samples indicates inequivalent Cu(1)O(2)Pb/Tl lengths and possible tilting of CuO 2 plane as a result of Mg2+ substitution. The increased ξc(0) and J as a result of the Ge4+ and Mg2+ substitutions are suggested to contributed to sustenance of superconductivity above 80 K in the samples.

AB - Substitution of Ge4+ in place of Cu in Tl0.85Cr 0.15Sr2CaCu2-xGexO 7-δ (x = 0-0.6) showed initial increase in zero critical temperature value, Tc zero from 98 K (x = 0) to 100 K (x = 0.1) and in the range of 85-86 K for x = 0.2-0.3. The slow decrease in Tc zero is unexpected as tetravalent Ge4+ substitution is expected to strongly reduce hole concentration in the samples and suppress Tc zero. Excess conductivity analyses of resistance versus temperature data based on Asmalazov-Larkin (AL) theory revealed that the substitution induced 2D-to-3D transition of fluctuation induced conductivity with the highest transition temperature, T 2D-3D observed at x = 0.1. FTIR spectroscopy analysis indicates Ge4+ substitution cause reduction in CuO 2/GeO2 interplanar distance while our calculation based on Lawrence-Doniach model revealed highest superconducting coherence length, ξc(0) and interplanar coupling, J at x = 0.3. On the other hand, substitution of divalent Mg2+ for Ca2+ in (Tl 0.5Pb0.5)(Sr1.8Yb0.2)(Ca 1-yMgy)Cu2O7 (y = 0-1.0), which is not expected to directly vary hole concentration, surprisingly caused Tc zero to increase from 89.6 K (y = 0) to an optimum value of 95.9 K (y = 0.6) before decreasing with further increase in y. Excess conductivity analyses showed 2D-to-3D transition of fluctuation induced conductivity for all samples where the highest T2D- 3D was at y = 0.4. Similar calculation revealed highest values of ξc(0) and J also at y = 0.4. FTIR analysis of the samples indicates inequivalent Cu(1)O(2)Pb/Tl lengths and possible tilting of CuO 2 plane as a result of Mg2+ substitution. The increased ξc(0) and J as a result of the Ge4+ and Mg2+ substitutions are suggested to contributed to sustenance of superconductivity above 80 K in the samples.

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