Abstract

In this work, we investigate the temperature dependence of the upper critical field, dH c2/dT, in an increasingly disordered NdFeAsO0.7F0.3 (NdFeAs(O,F)) single crystal that has been progressively irradiated up to a 5.25 ×1016 cm- 2 total particle dose. For the H||ab-plane, dH c2/dT does not vary remarkably with irradiation, while for the H||c-axis it increases sharply after the first irradiation of 3.60 ×1015 cm-2 and then more gradually with further irradiation doses. Focusing on the H||c-axis, we develop a phenomenological analysis of the H c2 slope which allows us to inspect the crossover from the clean to the dirty regime. From the H c2 slope normalized to the critical temperature and to its clean limit value, we extract the ratio of the coherence length ξ BCS to the mean free path and we find that when T c is reduced by a factor of four from its pristine value, ξ BCS/ becomes as large as ∼7 and reaches values of ∼1.8 nm, indicating that NdFeAs(O,F) is well into the dirty regime. Our analysis of the H c2 slope also allows us to compare the pair-breaking effectiveness of scattering in different superconductors, showing similarity between unconventional NdFeAs(O,F) and moderate-T c phonon-mediated devices, such as MgB2 and A15 compounds, but much a stronger difference with YBa2Cu3O7-δ. This work thus shows that dH c2/dT is a reliable parameter, providing an alternative to residual resistivity, for investigating the pair-breaking mechanism induced by impurity scattering in superconductors.

Original languageEnglish (US)
Article number034007
JournalSuperconductor Science and Technology
Volume31
Issue number3
DOIs
StatePublished - Feb 14 2018

Fingerprint

retarding
Irradiation
slopes
Superconducting materials
irradiation
Scattering
dosage
scattering
mean free path
Dosimetry
critical temperature
crossovers
Single crystals
Impurities
impurities
Temperature
temperature dependence
electrical resistivity
single crystals
barium copper yttrium oxide

Keywords

  • clean and dirty limit
  • irradiation
  • pair-breaking

ASJC Scopus subject areas

  • Ceramics and Composites
  • Condensed Matter Physics
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry

Cite this

Clean to dirty limit and T c suppression in NdFeAsO0.7F0.3 studied by H c2 analysis. / Pallecchi, I.; Tarantini, C.; Shen, Y.; Singh, Rakesh; Newman, Nathan; Cheng, P.; Jia, Y.; Wen, H. H.; Putti, M.

In: Superconductor Science and Technology, Vol. 31, No. 3, 034007, 14.02.2018.

Research output: Contribution to journalArticle

Pallecchi, I, Tarantini, C, Shen, Y, Singh, R, Newman, N, Cheng, P, Jia, Y, Wen, HH & Putti, M 2018, 'Clean to dirty limit and T c suppression in NdFeAsO0.7F0.3 studied by H c2 analysis', Superconductor Science and Technology, vol. 31, no. 3, 034007. https://doi.org/10.1088/1361-6668/aaaaa6
Pallecchi, I. ; Tarantini, C. ; Shen, Y. ; Singh, Rakesh ; Newman, Nathan ; Cheng, P. ; Jia, Y. ; Wen, H. H. ; Putti, M. / Clean to dirty limit and T c suppression in NdFeAsO0.7F0.3 studied by H c2 analysis. In: Superconductor Science and Technology. 2018 ; Vol. 31, No. 3.
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abstract = "In this work, we investigate the temperature dependence of the upper critical field, dH c2/dT, in an increasingly disordered NdFeAsO0.7F0.3 (NdFeAs(O,F)) single crystal that has been progressively irradiated up to a 5.25 ×1016 cm- 2 total particle dose. For the H||ab-plane, dH c2/dT does not vary remarkably with irradiation, while for the H||c-axis it increases sharply after the first irradiation of 3.60 ×1015 cm-2 and then more gradually with further irradiation doses. Focusing on the H||c-axis, we develop a phenomenological analysis of the H c2 slope which allows us to inspect the crossover from the clean to the dirty regime. From the H c2 slope normalized to the critical temperature and to its clean limit value, we extract the ratio of the coherence length ξ BCS to the mean free path and we find that when T c is reduced by a factor of four from its pristine value, ξ BCS/ becomes as large as ∼7 and reaches values of ∼1.8 nm, indicating that NdFeAs(O,F) is well into the dirty regime. Our analysis of the H c2 slope also allows us to compare the pair-breaking effectiveness of scattering in different superconductors, showing similarity between unconventional NdFeAs(O,F) and moderate-T c phonon-mediated devices, such as MgB2 and A15 compounds, but much a stronger difference with YBa2Cu3O7-δ. This work thus shows that dH c2/dT is a reliable parameter, providing an alternative to residual resistivity, for investigating the pair-breaking mechanism induced by impurity scattering in superconductors.",
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AU - Pallecchi, I.

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AU - Shen, Y.

AU - Singh, Rakesh

AU - Newman, Nathan

AU - Cheng, P.

AU - Jia, Y.

AU - Wen, H. H.

AU - Putti, M.

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AB - In this work, we investigate the temperature dependence of the upper critical field, dH c2/dT, in an increasingly disordered NdFeAsO0.7F0.3 (NdFeAs(O,F)) single crystal that has been progressively irradiated up to a 5.25 ×1016 cm- 2 total particle dose. For the H||ab-plane, dH c2/dT does not vary remarkably with irradiation, while for the H||c-axis it increases sharply after the first irradiation of 3.60 ×1015 cm-2 and then more gradually with further irradiation doses. Focusing on the H||c-axis, we develop a phenomenological analysis of the H c2 slope which allows us to inspect the crossover from the clean to the dirty regime. From the H c2 slope normalized to the critical temperature and to its clean limit value, we extract the ratio of the coherence length ξ BCS to the mean free path and we find that when T c is reduced by a factor of four from its pristine value, ξ BCS/ becomes as large as ∼7 and reaches values of ∼1.8 nm, indicating that NdFeAs(O,F) is well into the dirty regime. Our analysis of the H c2 slope also allows us to compare the pair-breaking effectiveness of scattering in different superconductors, showing similarity between unconventional NdFeAs(O,F) and moderate-T c phonon-mediated devices, such as MgB2 and A15 compounds, but much a stronger difference with YBa2Cu3O7-δ. This work thus shows that dH c2/dT is a reliable parameter, providing an alternative to residual resistivity, for investigating the pair-breaking mechanism induced by impurity scattering in superconductors.

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