Effect of nematic order on the spin fluctuation spectrum of LaFeAsO

ORAL

Abstract

Inelastic neutron scattering measurements on the LaFeAsO antiferromagnetic (AFM) system reveal distinct temperature-dependent behavior in the low-energy spin dynamics. As expected, the dynamic susceptibility at the AFM wavevector peaks at the AFM transition temperature $T_{\mathrm{N}}$, but also displays an anomaly at the orthorhombic-to-tetragonal transition temperature $T_{\mathrm{S}}$. The spin-spin correlation length increases rapidly below $T_{\mathrm{S}}$ once long-range nematic order sets in. The sharp changes in both the dynamic susceptibility and the spin-spin correlation length at $T_{\mathrm{S}}$ evidence a strong effect of nematic order on the magnetic spectrum, in agreement with models that attribute the structural transition to an electronic nematic phase driven by spin fluctuations.

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Authors

  • Qiang Zhang

    Ames Laboratory, U.S. DOE; Department of Physics and Astronomy, Iowa State University

  • Rafael Fernandes

    University of Minnesota, School of Physics and Astronomy, University of Minnesota

  • Jiaqiang Yan

    Ames Laboratory, U.S. DOE; Oak Ridge National Laboratory

  • R.W. McCallum

    The Ames Laboratory, Iowa State University, Ames, USA, Ames Laboratory, U.S. DOE; Division of Materials Sciences and Engineering, Iowa State University

  • Thomas A. Lograsso

    Ames Lab. Iowa State Univ., IA, Ames Laboratory, U.S. DOE; Division of Materials Sciences and Engineering, Iowa State University

  • Songxue Chi

    Oak Ridge National Lab, Oak Ridge National Laboratory

  • David Vaknin

    Ames Laboratory, U.S. DOE; Department of Physics and Astronomy, Iowa State University

  • Robert J. McQueeney

    Ames Laboratory and Iowa State University, Ames Lab. Iowa State Univ., IA, Ames Laboratory/ Iowa State University, Ames Laboratory and Dept. of Physics and Astronomy, Iowa State University, Ames Laboratory, U.S. DOE; Department of Physics and Astronomy, Iowa State University