Isotropic multi-gap superconductivity in BaFe1.9Pt0.1As2 from thermal transport and spectroscopic measurements

Steven Ziemak; K. Kirshenbaum; S. R. Saha; R. Hu; J. Ph Reid; R. Gordon; L. Taillefer; D. Evtushinsky; S. Thirupathaiah; B. Büchner; S. V. Borisenko; A. Ignatov; D. Kolchmeyer; G. Blumberg; J. Paglione

doi:10.1088/0953-2048/28/1/014004

Isotropic multi-gap superconductivity in BaFe_1.9Pt_0.1As₂ from thermal transport and spectroscopic measurements

Steven Ziemak
, K. Kirshenbaum
, S. R. Saha
, R. Hu
, J. Ph Reid
, R. Gordon
, L. Taillefer
, D. Evtushinsky
, S. Thirupathaiah
, B. Büchner
, S. V. Borisenko
, A. Ignatov
, D. Kolchmeyer
, G. Blumberg
, J. Paglione

School of Arts and Sciences, New High Energy Theory Center

Rutgers, The State University

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

Thermal conductivity, point contact spectroscopy, angle-resolved photoemission and Raman spectroscopy measurements were performed on BaFe_1.9Pt_0.1As₂ single crystals obtained from the same synthesis batch in order to investigate the superconducting energy gap structure using multiple techniques. Low temperature thermal conductivity was measured in the superconducting state as a function of temperature and magnetic field, revealing an absence of quasiparticle excitations in the limit up to 15 T applied magnetic fields. Point-contact Andreev reflection spectroscopy measurements were performed as a function of temperature using the needle-anvil technique, yielding features in the conductance spectra at both 2.5 meV and 7.0 meV scales consistent with a multi-gap scenario. Angle-resolved photoemission spectroscopy probed the electronic band structure above and below the superconducting transition temperature of T_c = 23 K, revealing an isotropic gap of magnitude meV on both electron and hole pockets. Finally, Raman spectroscopy was used to probe quasiparticle excitations in multiple channels, showing a threshold energy scale of 3 meV below T_c. Overall, we find strong evidence for an isotropic gap structure with no nodes or deep minima in this system, with a 3 meV magnitude gap consistently observed and a second, larger gap suggested by point-contact spectroscopy measurements. We discuss the implications that the combination of these results reveal about the superconducting order parameter in the BaFe₂-xPt xAs₂ doping system and how this relates to similar substituted iron pnictides.

Original language	American English
Article number	014004
Journal	Superconductor Science and Technology
Volume	28
Issue number	1
DOIs	https://doi.org/10.1088/0953-2048/28/1/014004
State	Published - Jan 1 2015

ASJC Scopus subject areas

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

Keywords

ARPES
Raman spectroscopy
iron pnictides
point contact spectroscopy
thermal conductivity

Access to Document

10.1088/0953-2048/28/1/014004

Cite this

Ziemak, S., Kirshenbaum, K., Saha, S. R., Hu, R., Reid, J. P., Gordon, R., Taillefer, L., Evtushinsky, D., Thirupathaiah, S., Büchner, B., Borisenko, S. V., Ignatov, A., Kolchmeyer, D., Blumberg, G., & Paglione, J. (2015). Isotropic multi-gap superconductivity in BaFe_1.9Pt_0.1As₂ from thermal transport and spectroscopic measurements. Superconductor Science and Technology, 28(1), Article 014004. https://doi.org/10.1088/0953-2048/28/1/014004

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title = "Isotropic multi-gap superconductivity in BaFe1.9Pt0.1As2 from thermal transport and spectroscopic measurements",

abstract = "Thermal conductivity, point contact spectroscopy, angle-resolved photoemission and Raman spectroscopy measurements were performed on BaFe1.9Pt0.1As2 single crystals obtained from the same synthesis batch in order to investigate the superconducting energy gap structure using multiple techniques. Low temperature thermal conductivity was measured in the superconducting state as a function of temperature and magnetic field, revealing an absence of quasiparticle excitations in the limit up to 15 T applied magnetic fields. Point-contact Andreev reflection spectroscopy measurements were performed as a function of temperature using the needle-anvil technique, yielding features in the conductance spectra at both 2.5 meV and 7.0 meV scales consistent with a multi-gap scenario. Angle-resolved photoemission spectroscopy probed the electronic band structure above and below the superconducting transition temperature of Tc = 23 K, revealing an isotropic gap of magnitude meV on both electron and hole pockets. Finally, Raman spectroscopy was used to probe quasiparticle excitations in multiple channels, showing a threshold energy scale of 3 meV below Tc. Overall, we find strong evidence for an isotropic gap structure with no nodes or deep minima in this system, with a 3 meV magnitude gap consistently observed and a second, larger gap suggested by point-contact spectroscopy measurements. We discuss the implications that the combination of these results reveal about the superconducting order parameter in the BaFe2-xPt xAs2 doping system and how this relates to similar substituted iron pnictides.",

keywords = "ARPES, Raman spectroscopy, iron pnictides, point contact spectroscopy, thermal conductivity",

author = "Steven Ziemak and K. Kirshenbaum and Saha, \{S. R.\} and R. Hu and Reid, \{J. Ph\} and R. Gordon and L. Taillefer and D. Evtushinsky and S. Thirupathaiah and B. B{\"u}chner and Borisenko, \{S. V.\} and A. Ignatov and D. Kolchmeyer and G. Blumberg and J. Paglione",

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Ziemak, S, Kirshenbaum, K, Saha, SR, Hu, R, Reid, JP, Gordon, R, Taillefer, L, Evtushinsky, D, Thirupathaiah, S, Büchner, B, Borisenko, SV, Ignatov, A, Kolchmeyer, D, Blumberg, G & Paglione, J 2015, 'Isotropic multi-gap superconductivity in BaFe_1.9Pt_0.1As₂ from thermal transport and spectroscopic measurements', Superconductor Science and Technology, vol. 28, no. 1, 014004. https://doi.org/10.1088/0953-2048/28/1/014004

TY - JOUR

T1 - Isotropic multi-gap superconductivity in BaFe1.9Pt0.1As2 from thermal transport and spectroscopic measurements

AU - Ziemak, Steven

AU - Kirshenbaum, K.

AU - Saha, S. R.

AU - Hu, R.

AU - Reid, J. Ph

AU - Gordon, R.

AU - Taillefer, L.

AU - Evtushinsky, D.

AU - Thirupathaiah, S.

AU - Büchner, B.

AU - Borisenko, S. V.

AU - Ignatov, A.

AU - Kolchmeyer, D.

AU - Blumberg, G.

AU - Paglione, J.

PY - 2015/1/1

Y1 - 2015/1/1

N2 - Thermal conductivity, point contact spectroscopy, angle-resolved photoemission and Raman spectroscopy measurements were performed on BaFe1.9Pt0.1As2 single crystals obtained from the same synthesis batch in order to investigate the superconducting energy gap structure using multiple techniques. Low temperature thermal conductivity was measured in the superconducting state as a function of temperature and magnetic field, revealing an absence of quasiparticle excitations in the limit up to 15 T applied magnetic fields. Point-contact Andreev reflection spectroscopy measurements were performed as a function of temperature using the needle-anvil technique, yielding features in the conductance spectra at both 2.5 meV and 7.0 meV scales consistent with a multi-gap scenario. Angle-resolved photoemission spectroscopy probed the electronic band structure above and below the superconducting transition temperature of Tc = 23 K, revealing an isotropic gap of magnitude meV on both electron and hole pockets. Finally, Raman spectroscopy was used to probe quasiparticle excitations in multiple channels, showing a threshold energy scale of 3 meV below Tc. Overall, we find strong evidence for an isotropic gap structure with no nodes or deep minima in this system, with a 3 meV magnitude gap consistently observed and a second, larger gap suggested by point-contact spectroscopy measurements. We discuss the implications that the combination of these results reveal about the superconducting order parameter in the BaFe2-xPt xAs2 doping system and how this relates to similar substituted iron pnictides.

AB - Thermal conductivity, point contact spectroscopy, angle-resolved photoemission and Raman spectroscopy measurements were performed on BaFe1.9Pt0.1As2 single crystals obtained from the same synthesis batch in order to investigate the superconducting energy gap structure using multiple techniques. Low temperature thermal conductivity was measured in the superconducting state as a function of temperature and magnetic field, revealing an absence of quasiparticle excitations in the limit up to 15 T applied magnetic fields. Point-contact Andreev reflection spectroscopy measurements were performed as a function of temperature using the needle-anvil technique, yielding features in the conductance spectra at both 2.5 meV and 7.0 meV scales consistent with a multi-gap scenario. Angle-resolved photoemission spectroscopy probed the electronic band structure above and below the superconducting transition temperature of Tc = 23 K, revealing an isotropic gap of magnitude meV on both electron and hole pockets. Finally, Raman spectroscopy was used to probe quasiparticle excitations in multiple channels, showing a threshold energy scale of 3 meV below Tc. Overall, we find strong evidence for an isotropic gap structure with no nodes or deep minima in this system, with a 3 meV magnitude gap consistently observed and a second, larger gap suggested by point-contact spectroscopy measurements. We discuss the implications that the combination of these results reveal about the superconducting order parameter in the BaFe2-xPt xAs2 doping system and how this relates to similar substituted iron pnictides.

KW - ARPES

KW - Raman spectroscopy

KW - iron pnictides

KW - point contact spectroscopy

KW - thermal conductivity

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U2 - 10.1088/0953-2048/28/1/014004

DO - 10.1088/0953-2048/28/1/014004

M3 - Article

SN - 0953-2048

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JO - Superconductor Science and Technology

JF - Superconductor Science and Technology

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