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Title: Temperature and polarization dependence of low-energy magnetic fluctuations in nearly optimally doped NaFe 0.9785 Co 0.0215 As

Abstract

We use unpolarized and polarized neutron scattering to study the temperature and polarization dependence of low-energy magnetic fluctuations in nearly optimally doped NaFe 0.9785Co 0.0215As, with coexisting superconductivity (T c ≈ 19 K) and weak antiferromagnetic order ( T N ≈ 30 K, ordered moment ≈ 0.02 μ B/Fe). A single spin resonance mode with intensity tracking the superconducting order parameter is observed, although energy of the mode only softens slightly upon approaching T c. Polarized neutron scattering reveals that the single resonance is mostly isotropic in spin space, similar to overdoped NaFe 0.935Co 0.045As but different from optimal electron-, hole-, and isovalently doped BaFe 2As 2 compounds, all featuring an additional prominent anisotropic component. Spin anisotropy in NaFe 0.9785Co 0.0215As is instead present at energies below the resonance, which becomes partially gapped below T c, similar to the situation in optimally doped YBa 2Cu 3O 6.9. Here, our results indicate that anisotropic spin fluctuations in NaFe1–xCoxAs appear in the form of a resonance in the underdoped regime, become partially gapped below T c near optimal doping, and disappear in overdoped compounds.

Authors:
 [1];  [1];  [1];  [2];  [3];  [3];  [4];  [5]; ORCiD logo [6];  [7];  [8]
  1. Rice Univ., Houston, TX (United States)
  2. Chinese Academy of Sciences (CAS), Beijing (China); Univ. of Chinese Academy of Sciences, Beijing (China)
  3. Beijing Normal Univ., Beijing (China)
  4. Forschungszentrum Julich GmbH, Garching (Germany)
  5. Univ. Grenoble Alpes, Grenoble (France)
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  7. Chinese Academy of Sciences (CAS), Beijing (China); Univ. of Chinese Academy of Sciences, Beijing (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)
  8. Rice Univ., Houston, TX (United States); Beijing Normal Univ., Beijing (China)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1409258
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 96; Journal Issue: 18; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Song, Yu, Wang, Weiyi, Zhang, Chenglin, Gu, Yanhong, Lu, Xingye, Tan, Guotai, Su, Yixi, Bourdarot, Frédéric, Christianson, Andrew D., Li, Shiliang, and Dai, Pengcheng. Temperature and polarization dependence of low-energy magnetic fluctuations in nearly optimally doped NaFe0.9785Co0.0215As. United States: N. p., 2017. Web. doi:10.1103/PhysRevB.96.184512.
Song, Yu, Wang, Weiyi, Zhang, Chenglin, Gu, Yanhong, Lu, Xingye, Tan, Guotai, Su, Yixi, Bourdarot, Frédéric, Christianson, Andrew D., Li, Shiliang, & Dai, Pengcheng. Temperature and polarization dependence of low-energy magnetic fluctuations in nearly optimally doped NaFe0.9785Co0.0215As. United States. doi:10.1103/PhysRevB.96.184512.
Song, Yu, Wang, Weiyi, Zhang, Chenglin, Gu, Yanhong, Lu, Xingye, Tan, Guotai, Su, Yixi, Bourdarot, Frédéric, Christianson, Andrew D., Li, Shiliang, and Dai, Pengcheng. Tue . "Temperature and polarization dependence of low-energy magnetic fluctuations in nearly optimally doped NaFe0.9785Co0.0215As". United States. doi:10.1103/PhysRevB.96.184512.
@article{osti_1409258,
title = {Temperature and polarization dependence of low-energy magnetic fluctuations in nearly optimally doped NaFe0.9785Co0.0215As},
author = {Song, Yu and Wang, Weiyi and Zhang, Chenglin and Gu, Yanhong and Lu, Xingye and Tan, Guotai and Su, Yixi and Bourdarot, Frédéric and Christianson, Andrew D. and Li, Shiliang and Dai, Pengcheng},
abstractNote = {We use unpolarized and polarized neutron scattering to study the temperature and polarization dependence of low-energy magnetic fluctuations in nearly optimally doped NaFe0.9785Co0.0215As, with coexisting superconductivity (Tc ≈ 19 K) and weak antiferromagnetic order (TN ≈ 30 K, ordered moment ≈ 0.02μB/Fe). A single spin resonance mode with intensity tracking the superconducting order parameter is observed, although energy of the mode only softens slightly upon approaching Tc. Polarized neutron scattering reveals that the single resonance is mostly isotropic in spin space, similar to overdoped NaFe0.935Co0.045As but different from optimal electron-, hole-, and isovalently doped BaFe2As2 compounds, all featuring an additional prominent anisotropic component. Spin anisotropy in NaFe0.9785Co0.0215As is instead present at energies below the resonance, which becomes partially gapped below Tc, similar to the situation in optimally doped YBa2Cu3O6.9. Here, our results indicate that anisotropic spin fluctuations in NaFe1–xCoxAs appear in the form of a resonance in the underdoped regime, become partially gapped below Tc near optimal doping, and disappear in overdoped compounds.},
doi = {10.1103/PhysRevB.96.184512},
journal = {Physical Review B},
issn = {2469-9950},
number = 18,
volume = 96,
place = {United States},
year = {2017},
month = {11}
}