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Spin Dynamics in the Antiferromagnetic Oxy- and Fluoro- Pnictides: LaMnAsO, LaMnSbO, and BaMnAsF

ORAL

Abstract

Inelastic neutron scattering (INS) from polycrystalline LaMnAsO, LaMnSbO, and BaMnAsF are analyzed using J1-J2-Jc Heisenberg model in the framework of the linear spin-wave theory. All three systems show clear evidence that J1 and J2 are both antiferromagnetic (AFM) with a ratio of 2J2/J1 < 1. Thus, the competing interactions do not lead to the stripe structure, preserving the square lattice checkerboard AFM structure. The inter-plane coupling Jc in all three systems is on the order of ≈ 3×10-4J1, rendering the magnetic properties of these systems quasi-two-dimensional. The substitution of Sb for As significantly lowers the in-plane exchange coupling, which is also reflected in the Néel temperature TN. Although BaMnAsF shares similar MnAs sheets as LaMnAsO, their J1-J2 values are substantially different. Using density functional theory, we calculate exchange parameters Jij to rationalize the differences between these systems.

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Presenters

  • FARHAN ISLAM

    Ames Laboratory, Iowa State University

Authors

  • FARHAN ISLAM

    Ames Laboratory, Iowa State University

  • Pinaki Das

    Ames Laboratory, Iowa State University, Dynamic Compression Sector (DCS), Washington State University

  • Yong Liu

    Ames Laboratory, Iowa State University, Ames Lab

  • Elijah Gordon

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

  • Liqin Ke

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

  • Douglas L Abernathy

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

  • 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

  • David Vaknin

    Ames Laboratory, Iowa State University, Ames Laboratory, Ames laboratory, Iowa State University