Spin pairing and penetration depth measurements from nuclear magnetic resonance in NaFe0.975Co0.025As

Sangwon Oh; A. M. Mounce; Jeongseop A. Lee; W. P. Halperin; C. L. Zhang; S. Carr; Pengcheng Dai

doi:10.1103/PhysRevB.87.174517

Spin pairing and penetration depth measurements from nuclear magnetic resonance in NaFe_0.975Co_0.025As

Sangwon Oh^*, A. M. Mounce, Jeongseop A. Lee, W. P. Halperin, C. L. Zhang, S. Carr, Pengcheng Dai

^*Corresponding author for this work

Physics and Astronomy

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

11 Scopus citations

Abstract

We have performed 75As nuclear magnetic resonance (NMR) Knight shift measurements on single crystals of NaFe_0.975Co_0.025As to show that its superconductivity is a spin-paired, singlet state consistent with predictions of the weak-coupling BCS theory. We use a spectator nucleus, 23Na, uncoupled from the superconducting condensate, to determine the diamagnetic magnetization and to correct for its effect on the 75As NMR spectra. The resulting temperature dependence of the spin susceptibility follows the Yosida function as predicted by BCS for an isotropic, single-valued energy gap. Additionally, we have analyzed the 23Na spectra that become significantly broadened by vortices to obtain the superconducting penetration depth as a function of temperature with λ_ab(0)=5327±78 Å.

Original language	English (US)
Article number	174517
Journal	Physical Review B - Condensed Matter and Materials Physics
Volume	87
Issue number	17
DOIs	https://doi.org/10.1103/PhysRevB.87.174517
State	Published - May 20 2013

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics

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title = "Spin pairing and penetration depth measurements from nuclear magnetic resonance in NaFe0.975Co0.025As",

abstract = "We have performed 75As nuclear magnetic resonance (NMR) Knight shift measurements on single crystals of NaFe0.975Co0.025As to show that its superconductivity is a spin-paired, singlet state consistent with predictions of the weak-coupling BCS theory. We use a spectator nucleus, 23Na, uncoupled from the superconducting condensate, to determine the diamagnetic magnetization and to correct for its effect on the 75As NMR spectra. The resulting temperature dependence of the spin susceptibility follows the Yosida function as predicted by BCS for an isotropic, single-valued energy gap. Additionally, we have analyzed the 23Na spectra that become significantly broadened by vortices to obtain the superconducting penetration depth as a function of temperature with λab(0)=5327±78 {\AA}.",

author = "Sangwon Oh and Mounce, {A. M.} and Lee, {Jeongseop A.} and Halperin, {W. P.} and Zhang, {C. L.} and S. Carr and Pengcheng Dai",

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doi = "10.1103/PhysRevB.87.174517",

language = "English (US)",

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T1 - Spin pairing and penetration depth measurements from nuclear magnetic resonance in NaFe0.975Co0.025As

AU - Oh, Sangwon

AU - Mounce, A. M.

AU - Lee, Jeongseop A.

AU - Halperin, W. P.

AU - Zhang, C. L.

AU - Carr, S.

AU - Dai, Pengcheng

PY - 2013/5/20

Y1 - 2013/5/20

N2 - We have performed 75As nuclear magnetic resonance (NMR) Knight shift measurements on single crystals of NaFe0.975Co0.025As to show that its superconductivity is a spin-paired, singlet state consistent with predictions of the weak-coupling BCS theory. We use a spectator nucleus, 23Na, uncoupled from the superconducting condensate, to determine the diamagnetic magnetization and to correct for its effect on the 75As NMR spectra. The resulting temperature dependence of the spin susceptibility follows the Yosida function as predicted by BCS for an isotropic, single-valued energy gap. Additionally, we have analyzed the 23Na spectra that become significantly broadened by vortices to obtain the superconducting penetration depth as a function of temperature with λab(0)=5327±78 Å.

AB - We have performed 75As nuclear magnetic resonance (NMR) Knight shift measurements on single crystals of NaFe0.975Co0.025As to show that its superconductivity is a spin-paired, singlet state consistent with predictions of the weak-coupling BCS theory. We use a spectator nucleus, 23Na, uncoupled from the superconducting condensate, to determine the diamagnetic magnetization and to correct for its effect on the 75As NMR spectra. The resulting temperature dependence of the spin susceptibility follows the Yosida function as predicted by BCS for an isotropic, single-valued energy gap. Additionally, we have analyzed the 23Na spectra that become significantly broadened by vortices to obtain the superconducting penetration depth as a function of temperature with λab(0)=5327±78 Å.

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Spin pairing and penetration depth measurements from nuclear magnetic resonance in NaFe_0.975Co_0.025As

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