Exploring magnetic frustration in a square-lattice metallic system: spin fluctuations in 15% Fe-doped CaCo<sub>2</sub>As<sub>2</sub>

ORAL

Abstract

Magnetic frustration can arise in a square lattice of magnetic moments from competition between nearest-neighbor (J1) and next-nearest-neighbor (J2) exchange, with η = J1/2J2 governing the magnetic ground state. Remarkably, our inelastic neutron scattering (INS) measurements have shown that CaCo1.86As2 is a unique example of a metallic square-lattice system with nearly perfect frustration (|η| ≈ 1) despite possessing 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. Instead of the walls of magnetic fluctuations found for x = 0, we rather find ferromagnetic-like fluctuations emerging from zone centers that, depending on the energy, is quickly suppressed with increasing momentum transfer. We discuss our results in terms of the changing degree of frustration with increasing x.

*This research was supported by the U.S. DOE, BES, 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 Laboratory, Ames, IA 50011, USA
    • Division of Materials Science & Engineering, Ames Laboratory
    • Ames Laboratory
    • Ames Lab

Authors

  • Benjamin Ueland

    • Ames Laboratory, Ames, IA 50011, USA
    • Division of Materials Science & Engineering, Ames Laboratory
    • Ames Laboratory
    • Ames Lab

  • Bing Li

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

  • Aashish Sapkota

    • Brookhaven national lab
    • Condensed Matter Physics & Materials Science Department, Brookhaven National Laboratory
    • Ames Laboratory, Ames, IA 50011, USA; Iowa State University, Ames, IA 50011, USA

  • Sangeetha Nediadath Sathyanadhan

    • Ames Laboratory, Ames, IA 50011, USA

  • David C Johnston

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

  • Alan Ira Goldman

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

  • Toby G. Perring

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

  • Andreas Kreyssig

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

  • Robert McQueeney

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