Evidence for biquadratic exchange in the quasi-two-dimensional antiferromagnet FePS3

FePS 3 is a van der Waals compound with a honeycomb lattice that is a good example of a two-dimensional antiferromagnet with Ising-like anisotropy. Neutron spectroscopy data from FePS 3 were previously analyzed using a straightforward Heisenberg Hamiltonian with a single-ion anisotropy. The analysis...

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Bibliographic Details
Published in:Journal of applied physics 2020-06, Vol.127 (22)
Main Authors: Wildes, A. R., Zhitomirsky, M. E., Ziman, T., Lançon, D., Walker, H. C.
Format: Article
Language:English
Subjects:
Anisotropy
Antiferromagnetism
Applied physics
Boundaries
Brillouin zones
Exchanging
Ising model
Magnons
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Summary:FePS 3 is a van der Waals compound with a honeycomb lattice that is a good example of a two-dimensional antiferromagnet with Ising-like anisotropy. Neutron spectroscopy data from FePS 3 were previously analyzed using a straightforward Heisenberg Hamiltonian with a single-ion anisotropy. The analysis captured most of the elements of the data; however, some significant discrepancies remained. The discrepancies were most obvious at the Brillouin zone boundaries. The data are subsequently reanalyzed, allowing for unequal exchange between nominally equivalent nearest-neighbors, which resolves the discrepancies. The source of the unequal exchange is attributed to a biquadratic exchange term in the Hamiltonian, which most probably arises from a strong magnetolattice coupling. The new parameters show that there are features consistent with Dirac magnon nodal lines along certain Brillouin zone boundaries.
ISSN:0021-8979
1089-7550
DOI:10.1063/5.0009114