Quantum critical nematic fluctuations and spin excitation anisotropy in the iron pnictides

ORAL

Abstract

Quantum criticality in the iron pnictides involves the nematic and antiferromagnetic channels in a concurrent way [1,2]. To elucidate the nematic correlations, we study the spin excitation anisotropy defined by the difference between the dynamical spin susceptibilities at (pi,0) and (0,pi) [3]. We consider an effective Ginzburg-Landau theory involving spin and Ising-nematic degrees of freedom [1,2] in the presence of a small external C4-symmetry-breaking potential. Our analysis is carried out in a large N limit [2]. We connect the spin excitation anisotropy to the dynamical spin susceptibility and the nematic susceptibility. This relationship provides the understanding of the singular energy dependences observed for the spin excitation anisotropy in the avoided quantum critical regime of the optimally Ni-doped BaFe2As2 under a uniaxial strain.

[1] J. Dai, Q. Si, J. X. Zhu, and E. Abrahams, PNAS 106, 4118, (2009).
[2] J. Wu, Q. Si and E. Abrahams, Phys. Rev. B 93, 104515 (2016).
[3] Y. Song, X. Lu, D. L. Abernathy, D. W. Tam, J. L. Niedziela, W. Tian, H. Luo, Q. Si, and P. Dai, Phys. Rev. B 92, 180504 (2015).

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Presenters

  • Elihu Abrahams

    University of California, Los Angeles

Authors

  • Elihu Abrahams

    University of California, Los Angeles

  • Chia-Chuan Liu

    Physics and Astronomy, Rice Univ, Rice Universiry, Rice Univ

  • Qimiao Si

    Department of Physics and Astronomy, Rice University, Physics and Astronomy, Rice Univ, Physics and Astronomy, Rice University, Rice Univ, Rice Universiry, Physics, Rice University, Rice University, Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Physics and Astronomy, and Rice Center for Quantum Materials, Rice University, Department of Physics and Astronomy, Rice Univ