Spin Dynamics and Spin-flop transition in Magnetoelectric Effect LiMnPO$_{4}$

ORAL

Abstract

Neutron scattering techniques were used to study~the magnetic phase transition and spin dynamics in single crystal~LiMnPO$_{4}$ both with and without magnetic field.~~Elastic scattering confirmed that~LiMnPO$_{4}$ has a collinear antiferromagnetic ground state with~moments along $a$-axis in zero-field. The temperature dependent~order parameter, calculated from the integrated intensity of the (010)~magnetic reflection, was fit to a power law equation, yielding a~transition temperature $T_{N}$ = 33.8 K. By applying magnetic field along the a-axis, the moments rotate from a-axis to the c-axis at a critical field of 3.5 Tesla at 5 K.~ The field dependent (100) and (001) intensities indicate a complicated intermediate state between the ground state and the spin-flop state. The critical field increased from 3.5 Tesla at 5 K to 4.5 Tesla near the transition $T_{N}$. Spin-wave dispersion curves along the three principal axes were measured in the antiferromagnetic state at 4.5 K in zero magnetic field and were analyzed using a 3D Heisenberg~model.

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Authors

  • J. Li

    • NCNR, National Institute of Standards and Technology; Dept. Material Science and Engineering, University of Maryland

  • W. Tian

    • Oak Ridge National Laboratory, Oak Ridge TN 37831
    • Ames laboratory and Dept. of Physics and Astronomy, Iowa State University

  • Y. Chen

    • NCNR, National Institute of Standards and Technology; Dept. Material Science and Engineering, University of Maryland

  • J.L. Zarestky

    • Ames laboratory and Dept. of Physics and Astronomy, Iowa State University, Ames, IA 50011
    • Ames laboratory and Dept. of Physics and Astronomy, Iowa State University

  • D. Vaknin

    • Ames laboratory and Dept. of Physics and Astronomy, Iowa State University, Ames, IA 50011
    • Ames laboratory and Dept. of Physics and Astronomy, Iowa State University

  • J. W. Lynn

    • National Institute of Standards and Technology
    • NIST Center for Neutron Scattering
    • NIST
    • NCNR, National Institute of Standards and Technology, Gaithersburg, MD 20899
    • NCNR, National Institute of Standards and Technology