51 research outputs found
Antiferromagnetism in the magnetoelectric effect single crystal LiMnPO
Elastic and inelastic neutron scattering studies reveal details of the
antiferromagnetic tansition and intriguing spin-dynamics in the
magneto-electric effect single crystal LiMnPO. The elastic scattering
studies confirm the system is antiferromagnetic (AFM) below =33.75 K with
local magnetic moments (Mn; ) that are aligned along the
crystallographic a-axis. The spin-wave dispersion curves propagating along the
three principal axes, determined by inelastic scattering, are adequately
modeled in the linear spin-wave framework assuming a spin-Hamiltonian that is
parameterized by inter- and in-plane nearest- and next-nearest-neighbor
interactions, and by easy-plane anisotropy. The temperature dependence of the
spin dynamics makes this an excellent model many-body spin system to address
the question of the relationship between spin-wave excitations and the order
parameter
Spin Dynamics in the Magnetoelectric Effect LiCoPO Compound
Inelastic neutron scattering (INS) experiments were performed to investigate
the spin dynamics in magnetoelectric effect (ME) LiCoPO single crystals.
Weak dispersion was detected in the magnetic excitation spectra along the three
principal crystallographic axes measured around the (0 1 0) magnetic
reflection. Analysis of the data using linear spin-wave theory indicate that
single-ion anisotropy in LiCoPO is as important as the strongest
nearest-neighbor exchange coupling. Our results suggest that Co
single-ion anisotropy plays an important role in the spin dynamics of
LiCoPO and must be taken into account in understanding its physical
properties. High resolution INS measurements reveal an anomalous low energy
excitation that we hypothesize may be related to the magnetoelectric effect of
LiCoPO.Comment: 6 pages, 5 figures, accepted for publication in Phys. Rev.
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