Neutron diffraction studies of the composition induced moment reorientation in antiferromagnetically ordered Ca<sub>1-<i>x</i></sub>Sr<i><sub>x</sub></i>Co<sub>2</sub>As<sub>2</sub>

ORAL

Abstract

ACo2As2 (A = Ca, Sr, Ba) are tetragonal itinerant magnets that display a dichotomy typical of their As-As hybridization-driven magnetoelastic interactions: CaCo2As2 has A-type antiferromagnetic (AFM) order with Co ordered moments aligned along c, and SrCo2As2 and BaCo2As2 do not order. Ca1-xSrxCo2As2 shows a series of magnetic phases, with transitions between them at x ≈ 0.2, 0.3, and 0.5. Magnetization data show A-type order as in CaCo2As2 for x < 0.2 and no magnetic order for x > 0.5. Here, we present and discuss quantitative results from neutron and high-energy x-ray diffraction experiments on single crystals with x = 0.25 and 0.40. Rather than A-type order, we find extremely weak magnetic Bragg peaks corresponding to a propagation vector of (0, 0, 0.5) for both samples. The ordered moment lies along c for x = 0.25 but in the ab plane for x = 0.40. No structural phase transitions accompany the AFM transitions.

*Work at the Ames Laboratory was supported by the U.S. DOE, BES, DMSE under Contract No. DE-AC02-07CH11358. This research used resources at the High Flux Isotope Reactor and Advanced Photon Source, which are U.S. DOE Office of Science User Facilities.

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Presenters

  • Benjamin Ueland

    • Ames Laboratory, Iowa State University
    • Ames Laboratory/Iowa State University

Authors

  • Bing Li

    • Ames Laboratory, Iowa State University
    • Ames Laboratory, Iowa State University, Dept. of Physics and Astronomy, Ames
    • Ames Laboratory/Iowa State University

  • Sangeetha N. S.

    • Ames Laboratory, Iowa State University
    • Ames Laboratory/Iowa State University

  • John Wilde

    • Ames Laboratory/Iowa State University
    • Ames Laboratory, Iowa State University

  • Wei Tian

    • Neutron Scattering Division, Oak Ridge National Laboratory
    • Oak Ridge National Laboratory

  • Andreas Kreyssig

    • Ames Laboratory and Dept. of Physics, Iowa State University
    • Ames Laboratory, Iowa State University
    • Ames Laboratory, Iowa State University, Dept. of Physics and Astronomy, Ames
    • Ames Laboratory/Iowa State University
    • Ames Laboratory & Department of Physics, Iowa State University

  • Benjamin Ueland

    • Ames Laboratory, Iowa State University
    • Ames Laboratory/Iowa State University

  • David C Johnston

    • Ames Laboratory, Iowa State University
    • Ames Laboratory/Iowa State University

  • Alan Ira Goldman

    • Ames Laboratory, Iowa State University
    • Ames Laboratory/Iowa State University

  • Robert McQueeney

    • Ames Laboratory, Iowa State University
    • Ames Laboratory
    • Ames Laboratory/Iowa State University