Onset of two-dimensional Stoner magnetism in cobalt arsenides

ORAL

Abstract

CaCo1.86As2 is a unique example of a metallic square-lattice system with nearly perfect frustration despite the compound having A-type antiferromagnetic (AF) order below a Néel temperature of TN = 52 K. Our recent neutron diffraction data on Ca(Co1-xFex)2-yAs2 show that the A-type AF order is suppressed past x = 0.12, and here we give results from INS experiments made at T = 6 K on single-crystal samples of x = 0.15. We find diffuse spin fluctuations giving rise to walls of magnetic scattering with similar anisotropy to that found for x = 0, however, the fluctuating moment is extremely weak. A simultaneous analysis of magnetic susceptibility and neutron scattering data shows that the total magnetic moment is gradually reduced with increasing x. This suggests that the development of magnetic order has a Stoner-like mechanism where Fe-doping acts to tune (and decrease) the Stoner parameter UN(EF). This highlights that cobalt arsenides are uniquely frustrated and weakly itinerant magnets.

*This research was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Contract No. DE-AC02-07CH11358. We gratefully acknowledge the Science and Technology Facilities Council (STFC) for access to neutron beamtime at ISIS.

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Presenters

  • Benjamin Ueland

    • Ames Lab
    • Physics and Astronomy, Iowa State University/Ames Laboratory
    • Division of Materials Science & Engineering, Ames Laboratory
    • Ames Laboratory and Iowa State University, Ames, IA USA 50011
    • Ames Laboratory/Iowa State University

Authors

  • Benjamin Ueland

    • Ames Lab
    • Physics and Astronomy, Iowa State University/Ames Laboratory
    • Division of Materials Science & Engineering, Ames Laboratory
    • Ames Laboratory and Iowa State University, Ames, IA USA 50011
    • Ames Laboratory/Iowa State University

  • Bing Li

    • Ames Laboratory, Iowa State University, Dept. of Physics and Astronomy, Ames
    • Ames Laboratory and Iowa State Univeristy
    • Ames Laboratory and Iowa State University, Ames, IA USA 50011

  • Santanu Pakhira

    • Ames Laboratory and Iowa State University, Ames, IA USA 50011

  • Aashish Sapkota

    • Brookhaven National Laboratory
    • Ames Laboratory and Iowa State University, Ames, IA USA 50011

  • Sangeetha Nediadath Sathyanadhan

    • Ames Laboratory and Iowa State University, Ames, IA USA 50011

  • Toby G Perring

    • Neutron and Muon Source, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 OQX, UK

  • David C Johnston

    • Department of Physics and Astronomy, Ames Laboratory, Iowa State University
    • Ames Laboratory and Iowa State University, Ames, IA USA 50011

  • Robert J McQueeney

    • Ames Lab
    • Physics and Astronomy, Iowa State University/Ames Laboratory
    • Department of Physics and Astronomy, Ames Laboratory, Iowa State University
    • Ames Lab/Iowa State
    • Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, USA
    • Iowa State University
    • Ames Laboratory and Iowa State University, Ames, IA USA 50011
    • Ames Laboratory/Iowa State University