As75 NMR of Ba(Fe0.93Co0.07)2As 2 in high magnetic field

Sangwon Oh; A. M. Mounce; S. Mukhopadhyay; W. P. Halperin; A. B. Vorontsov; S. L. Bud'Ko; P. C. Canfield; Y. Furukawa; A. P. Reyes; P. L. Kuhns

doi:10.1103/PhysRevB.83.214501

As75 NMR of Ba(Fe_0.93Co_0.07)₂As ₂ in high magnetic field

Sangwon Oh^*, A. M. Mounce, S. Mukhopadhyay, W. P. Halperin, A. B. Vorontsov, S. L. Bud'Ko, P. C. Canfield, Y. Furukawa, A. P. Reyes, P. L. Kuhns

^*Corresponding author for this work

Physics and Astronomy

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Abstract

The superconducting state of an optimally doped single crystal of Ba(Fe_0.93Co_0.07)₂As₂ was investigated by As75 NMR in high magnetic fields from 6.4 to 28 T. It was found that the Knight shift is least affected by vortex supercurrents in high magnetic fields H 11 T, revealing slow, possibly higher order than linear, increase with temperature at T_c, with T_c23 K. This is consistent with the extended s-wave state with A_1g symmetry, but the precise details of the gap structure are harder to resolve. Measurements of the NMR spin-spin relaxation time T₂ indicate a strong indirect exchange interaction at all temperatures. Below the superconducting transition temperature, abrupt changes in vortex dynamics lead to an anomalous dip in T₂, consistent with vortex freezing from which we obtain the vortex phase diagram up to H=28 T.

Original language	English (US)
Article number	214501
Journal	Physical Review B - Condensed Matter and Materials Physics
Volume	83
Issue number	21
DOIs	https://doi.org/10.1103/PhysRevB.83.214501
State	Published - Jun 1 2011

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics

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title = "As75 NMR of Ba(Fe0.93Co0.07)2As 2 in high magnetic field",

abstract = "The superconducting state of an optimally doped single crystal of Ba(Fe0.93Co0.07)2As2 was investigated by As75 NMR in high magnetic fields from 6.4 to 28 T. It was found that the Knight shift is least affected by vortex supercurrents in high magnetic fields H 11 T, revealing slow, possibly higher order than linear, increase with temperature at Tc, with Tc23 K. This is consistent with the extended s-wave state with A1g symmetry, but the precise details of the gap structure are harder to resolve. Measurements of the NMR spin-spin relaxation time T2 indicate a strong indirect exchange interaction at all temperatures. Below the superconducting transition temperature, abrupt changes in vortex dynamics lead to an anomalous dip in T2, consistent with vortex freezing from which we obtain the vortex phase diagram up to H=28 T.",

author = "Sangwon Oh and Mounce, {A. M.} and S. Mukhopadhyay and Halperin, {W. P.} and Vorontsov, {A. B.} and Bud'Ko, {S. L.} and Canfield, {P. C.} and Y. Furukawa and Reyes, {A. P.} and Kuhns, {P. L.}",

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doi = "10.1103/PhysRevB.83.214501",

language = "English (US)",

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T1 - As75 NMR of Ba(Fe0.93Co0.07)2As 2 in high magnetic field

AU - Oh, Sangwon

AU - Mounce, A. M.

AU - Mukhopadhyay, S.

AU - Halperin, W. P.

AU - Vorontsov, A. B.

AU - Bud'Ko, S. L.

AU - Canfield, P. C.

AU - Furukawa, Y.

AU - Reyes, A. P.

AU - Kuhns, P. L.

PY - 2011/6/1

Y1 - 2011/6/1

N2 - The superconducting state of an optimally doped single crystal of Ba(Fe0.93Co0.07)2As2 was investigated by As75 NMR in high magnetic fields from 6.4 to 28 T. It was found that the Knight shift is least affected by vortex supercurrents in high magnetic fields H 11 T, revealing slow, possibly higher order than linear, increase with temperature at Tc, with Tc23 K. This is consistent with the extended s-wave state with A1g symmetry, but the precise details of the gap structure are harder to resolve. Measurements of the NMR spin-spin relaxation time T2 indicate a strong indirect exchange interaction at all temperatures. Below the superconducting transition temperature, abrupt changes in vortex dynamics lead to an anomalous dip in T2, consistent with vortex freezing from which we obtain the vortex phase diagram up to H=28 T.

AB - The superconducting state of an optimally doped single crystal of Ba(Fe0.93Co0.07)2As2 was investigated by As75 NMR in high magnetic fields from 6.4 to 28 T. It was found that the Knight shift is least affected by vortex supercurrents in high magnetic fields H 11 T, revealing slow, possibly higher order than linear, increase with temperature at Tc, with Tc23 K. This is consistent with the extended s-wave state with A1g symmetry, but the precise details of the gap structure are harder to resolve. Measurements of the NMR spin-spin relaxation time T2 indicate a strong indirect exchange interaction at all temperatures. Below the superconducting transition temperature, abrupt changes in vortex dynamics lead to an anomalous dip in T2, consistent with vortex freezing from which we obtain the vortex phase diagram up to H=28 T.

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JO - Physical Review B - Condensed Matter and Materials Physics

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ER -

As75 NMR of Ba(Fe_0.93Co_0.07)₂As ₂ in high magnetic field

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