FePS3 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 FePS3 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.

1.
G.
Ouvrard
,
R.
Brec
, and
J.
Rouxel
,
Mater. Res. Bull.
20
,
1181
(
1985
).
2.
P.
Jernberg
,
S.
Bjarman
, and
R.
Wäppling
,
J. Magn. Magn. Mater.
46
,
178
190
(
1984
).
3.
P. A.
Joy
and
S.
Vasudevan
,
Phys. Rev. B
46
,
5425
(
1992
).
4.
K.
Kurosawa
,
S.
Saito
, and
Y.
Yamaguchi
,
J. Phys. Soc. Jpn.
52
,
3919
3926
(
1983
).
5.
D.
Lançon
,
H. C.
Walker
,
E.
Ressouche
,
B.
Ouladdiaf
,
K. C.
Rule
,
G. J.
McIntyre
,
T. J.
Hicks
,
H. M.
Rønnow
, and
A. R.
Wildes
,
Phys. Rev. B
94
,
214407
(
2016
).
7.
V.
Grasso
and
L.
Silipigni
,
Riv. Nuovo Cimento
25
,
1
(
2002
).
8.
M. A.
Susner
,
M.
Chyasnavichyus
,
M. A.
McGuire
,
P.
Ganesh
, and
P.
Maksymovych
,
Adv. Mater.
29
,
1602852
(
2017
).
9.
F.
Wang
,
T. A.
Shifa
,
P.
Yu
,
P.
He
,
Y.
Liu
,
F.
Wang
,
Z.
Wang
,
X.
Zhan
,
X.
Lou
,
F.
Xia
, and
J.
He
,
Adv. Funct. Mater.
28
,
1802151
(
2018
).
10.
M. J.
Coak
,
D. M.
Jarvis
,
H.
Hamidov
,
C. R. S.
Haines
,
P. L.
Alireza
,
C.
Liu
,
S.
Son
,
I.
Hwang
,
G. I.
Lampronti
,
D.
Daisenberger
,
P.
Nahai-Williamson
,
A. R.
Wildes
,
S. S.
Saxena
, and
J.-G.
Park
, “
Tuning dimensionality in van-der-waals antiferromagnetic mott insulators TMPS3
,”
J. Phys. Condens. Matter
32
,
124003
(
2019
).
11.
Y.
Wang
,
J.
Ying
,
Z.
Zhou
,
J.
Sun
,
T.
Wen
,
Y.
Zhou
,
N.
Li
,
Q.
Zhang
,
F.
Han
,
Y.
Xiao
,
P.
Chow
,
W.
Yang
,
V. V.
Struzhkin
,
Y.
Zhao
, and
H.-K.
Mao
,
Nat. Commun.
9
,
1914
(
2018
).
12.
13.
J.-U.
Lee
,
S.
Lee
,
J. H.
Ryoo
,
S.
Kang
,
T. Y.
Kim
,
P.
Kim
,
C.-H.
Park
,
J.-G.
Park
, and
H.
Cheong
,
Nano Lett.
16
,
7433
7438
(
2016
).
14.
A. R.
Wildes
,
K. C.
Rule
,
R. I.
Bewley
,
M.
Enderle
, and
T. J.
Hicks
,
J. Phys. Condens. Matter
24
,
416004
(
2012
).
15.
E. M.
Wheeler
,
R.
Coldea
,
E.
Wawrzyńska
,
T.
Sörgel
,
M.
Jansen
,
M. M.
Koza
,
J.
Taylor
,
P.
Adroguer
, and
N.
Shannon
,
Phys. Rev. B
79
,
104421
(
2009
).
16.
E.
Rastelli
,
A.
Tassi
, and
L.
Reatto
,
Physica B
97
,
1
24
(
1979
).
17.
E.
Rastelli
,
A.
Tassi
, and
L.
Reatto
,
J. Magn. Magn. Mater.
15–18
,
357
358
(
1980
).
18.
A. R.
Wildes
,
D.
Lançon
,
M. K.
Chan
,
F.
Weickert
,
N.
Harrison
,
V.
Simonet
,
M. E.
Zhitomirsky
,
M. V.
Gvozdikova
,
T.
Ziman
, and
H. M.
Rønnow
, “
High field magnetization of FePS3
,”
Phys. Rev. B
101
,
024415
(
2020
).
19.
A. L.
Wysocki
,
K. D.
Belashchenko
, and
V. P.
Antropov
,
Nat. Phys.
7
,
485
489
(
2011
).
20.
A. L.
Wysocki
,
K. D.
Belashchenko
,
L.
Ke
,
M.
van Schilfgaarde
, and
V. P.
Antropov
,
J. Phys. Conf. Ser.
449
,
012024
(
2013
).
21.
C.
Murayama
,
M.
Okabe
,
D.
Urushihara
,
T.
Asaka
,
K.
Fukuda
,
M.
Isobe
,
K.
Yamamoto
, and
Y.
Matsushita
,
J. Appl. Phys.
120
,
142114
(
2016
).
22.
B. L.
Chittari
,
Y.
Park
,
D.
Lee
,
M.
Han
,
A. H.
MacDonald
,
E.
Hwang
, and
J.
Jung
, “
Electronic and magnetic properties of single-layer mPX3 metal phosphorous trichalcogenides
,”
Phys. Rev. B
94
,
184428
(
2016
).
23.
Y.
Gu
,
Q.
Zhang
,
C.
Le
,
Y.
Li
,
T.
Xiang
, and
J.
Hu
, “
Ni-based transition metal trichalcogenide monolayer: A strongly correlated quadruple-layer graphene
,”
Phys. Rev. B
100
,
165405
(
2019
).
24.
F.
Mila
and
F.-C.
Zhang
,
Eur. Phys. J. B
16
,
7
10
(
2000
).
25.
K.
Tanaka
,
Y.
Yokoyama
, and
C.
Hotta
, “
Origin of biquadratic exchange interactions in a mott insulator as a driving force of spin nematic order
,”
J. Phys. Soc. Jpn.
87
,
023702
(
2018
).
26.
K.
Penc
,
N.
Shannon
, and
H.
Shiba
, “
Half-magnetization plateau stabilized by structural distortion in the antiferromagnetic heisenberg model on a pyrochlore lattice
,”
Phys. Rev. Lett.
93
,
197203
(
2004
).
27.
G. L.
Flem
,
R.
Brec
,
G.
Ouvard
,
A.
Louisy
, and
P.
Segransan
, “
Magnetic interactions in the layer compounds MPX3 (M = Mn, Fe, Ni; X = S, Se)
,”
J. Phys. Chem. Solids
43
,
455
461
(
1982
), ISSN 0022-3697.
28.
D.
Lançon
,
R. A.
Ewings
,
T.
Guidi
,
F.
Formisano
, and
A. R.
Wildes
, “
Magnetic exchange parameters and anisotropy of the quasi-two-dimensional antiferromagnet NiPS3
,”
Phys. Rev. B
98
,
134414
(
2018
).
30.
S. S.
Pershoguba
,
S.
Banerjee
,
J. C.
Lashley
,
J.
Park
,
H.
Ågren
,
G.
Aeppli
, and
A. V.
Balatsky
, “
Dirac magnons in honeycomb ferromagnets
,”
Phys. Rev. X
8
,
011010
(
2018
).
You do not currently have access to this content.