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Title: Superconducting gap evolution in overdoped BaFe₂(As 1-xP x)₂ single crystals through nanocalorimetry

We report on specific heat measurements on clean overdoped BaFe₂(As 1-xP x)₂ single crystals performed with a high resolution membrane-based nanocalorimeter. A nonzero residual electronic specific heat coefficient at zero temperature γr=C/T| T→0 is seen for all doping compositions, indicating a considerable fraction of the Fermi surface ungapped or having very deep minima. The remaining superconducting electronic specific heat is analyzed through a two-band s-wave α model in order to investigate the gap structure. Close to optimal doping we detect a single zero-temperature gap of Δ₀~5.3 me V, corresponding to Δ₀/k BT c ~ 2.2. Increasing the phosphorus concentration x, the main gap reduces till a value of Δ₀ ~ 1.9 meV for x = 0.55 and a second weaker gap becomes evident. From the magnetic field effect on γ r, all samples however show similar behavior [γ r(H) - γ r (H = 0)∝ H n, with n between 0.6 and 0.7]. This indicates that, despite a considerable redistribution of the gap weights, the total degree of gap anisotropy does not change drastically with doping.
Authors:
; ; ; ; ;
Publication Date:
Type:
Publisher's Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Volume: 91 Journal Issue: 24; Journal ID: ISSN 1098-0121
Publisher:
American Physical Society
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
OSTI Identifier:
1186724

Campanini, D., Diao, Z., Fang, L., Kwok, W.-K., Welp, U., and Rydh, A.. Superconducting gap evolution in overdoped BaFe₂(As1-xPx)₂ single crystals through nanocalorimetry. United States: N. p., Web. doi:10.1103/PhysRevB.91.245142.
Campanini, D., Diao, Z., Fang, L., Kwok, W.-K., Welp, U., & Rydh, A.. Superconducting gap evolution in overdoped BaFe₂(As1-xPx)₂ single crystals through nanocalorimetry. United States. doi:10.1103/PhysRevB.91.245142.
Campanini, D., Diao, Z., Fang, L., Kwok, W.-K., Welp, U., and Rydh, A.. 2015. "Superconducting gap evolution in overdoped BaFe₂(As1-xPx)₂ single crystals through nanocalorimetry". United States. doi:10.1103/PhysRevB.91.245142.
@article{osti_1186724,
title = {Superconducting gap evolution in overdoped BaFe₂(As1-xPx)₂ single crystals through nanocalorimetry},
author = {Campanini, D. and Diao, Z. and Fang, L. and Kwok, W.-K. and Welp, U. and Rydh, A.},
abstractNote = {We report on specific heat measurements on clean overdoped BaFe₂(As1-xPx)₂ single crystals performed with a high resolution membrane-based nanocalorimeter. A nonzero residual electronic specific heat coefficient at zero temperature γr=C/T|T→0 is seen for all doping compositions, indicating a considerable fraction of the Fermi surface ungapped or having very deep minima. The remaining superconducting electronic specific heat is analyzed through a two-band s-wave α model in order to investigate the gap structure. Close to optimal doping we detect a single zero-temperature gap of Δ₀~5.3 me V, corresponding to Δ₀/kBTc ~ 2.2. Increasing the phosphorus concentration x, the main gap reduces till a value of Δ₀ ~ 1.9 meV for x = 0.55 and a second weaker gap becomes evident. From the magnetic field effect on γr, all samples however show similar behavior [γr(H) - γr (H = 0)∝ Hn, with n between 0.6 and 0.7]. This indicates that, despite a considerable redistribution of the gap weights, the total degree of gap anisotropy does not change drastically with doping.},
doi = {10.1103/PhysRevB.91.245142},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 24,
volume = 91,
place = {United States},
year = {2015},
month = {6}
}

Works referenced in this record:

Pairing symmetry in cuprate superconductors
journal, October 2000