Antiferromagnetic spin correlations in the tetragonal phase of CaFe$_{2}$As$_{2}$

ORAL

Abstract

We present neutron scattering measurements of magnetic excitations in the tetragonal phase of CaFe$_{2}$As$_{2}$. Below $T_{S}$ = 173 K, CaFe$_{2}$As$_{2}$ undergoes a first-order transition to an orthorhombic structure with columnar antiferromagnetic ordering with a wavevector \textbf{Q}$_{AFM}$ = (101). This phase is characterized by strong magnetic interactions giving rise to steep spin waves. In the tetragonal phase above $T_{S}$, broad quasi-elastic excitations are observed near \textbf{Q}$_{AFM}$ that display a weak dependence on $L$, indicating two-dimensional antiferromagnetic correlations. These correlations are observed to persist up excitation energies of $\sim $50 meV and temperatures of at least 300 K. Our results indicate that strong magnetic interactions exist above $T_{S}$, and ordering is likely suppressed by magnetic frustration.

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Authors

  • R.J. McQueeney

    • Ames Laboratory and Physics Department and Astronomy, Iowa State University, Ames, IA
    • Ames Laboratory and Iowa State University
    • Ames Laboratory, US DOE and Iowa State University
    • Ames Laboratory
    • Ames Laboratory/Department of Physics and Astronomy

  • S.O. Diallo

    • Ames Laboratory, US DOE and Iowa State University

  • J.L. Zarestky

    • Ames Laboratory and Physics Department and Astronomy, Iowa State University, Ames, IA
    • Ames Laboratory, US DOE and Iowa State University

  • Collin Broholm

    • Johns Hopkins University

  • T.G. Perring

    • Rutherford Appleton Laboratory

  • S.L. Bud'ko

    • Ames Laboratory and Iowa State University
    • Ames Laboratory and Physics Department and Astronomy, Iowa State University, Ames, IA
    • Ames Laboratory
    • Ames Laboratory, US DOE and Iowa State University
    • Ames Laboratory/Iowa State University
    • Ames Laboratory/Department of Physics and Astronomy
    • Ames laboratory

  • N. Ni

    • Ames Laboratory and Iowa State University
    • Ames Laboratory and Physics Department and Astronomy, Iowa State University, Ames, IA
    • Ames Lab / Iowa State University
    • Ames Laboratory, US DOE and Iowa State University
    • Iowa State University
    • Ames Laboratory/Department of Physics and Astronomy

  • Andreas Kreyssig

    • Ames Laboratory and Physics Department and Astronomy, Iowa State University, Ames, IA
    • Ames Laboratory and Iowa State University
    • Ames Laboratory, US DOE and Iowa State University
    • Ames Laboratory/Department of Physics and Astronomy
    • Ames Laboratory, US DOE, Iowa State University, Ames, IA 5001, USA

  • P.C. Canfield

    • Ames Laboratory and Department of Physics and Astronomy, Iowa State Univeristy, Ames, Iowa 50011
    • Ames Laboratory and Iowa State University
    • Ames Laboratory and Physics Department and Astronomy, Iowa State University, Ames, IA
    • Ames Laboratory
    • Ames Laboratory, US DOE and Iowa State University
    • Ames Laboratory/Department of Physics and Astronomy
    • Ames Lab / Iowa State University
    • Ames Laboratory/Iowa State University

  • Alan Goldman

    • Ames Laboratory and Physics Department and Astronomy, Iowa State University, Ames, IA
    • Ames Laboratory and Iowa State University
    • Ames Laboratory, US DOE and Iowa State University
    • Ames Laboratory
    • Ames Loboratory, US DOE and Iowa State University
    • Ames Laboratory/Department of Physics and Astronomy
    • Ames Laboratory, US DOE, Iowa State University, Ames, IA 5001, USA