Details
| Original language | English |
|---|---|
| Pages (from-to) | 5947-5956 |
| Number of pages | 10 |
| Journal | Journal of Physical Chemistry C |
| Volume | 125 |
| Issue number | 10 |
| Early online date | 4 Mar 2021 |
| Publication status | Published - 18 Mar 2021 |
| Externally published | Yes |
Abstract
The ground state of Fe2+ (S = 2) in α- and β-FeMoO4 is investigated by experiments including X-ray diffraction, Raman scattering, and 57Fe-Mössbauer spectroscopy below 300 K and evaluated by theoretical modeling. Both modifications crystallize in the space group C2/m with the same set of Wyckoff positions. The structural feature of α- and β-FeMoO4 is a tetramer of the so-called butterfly motif. Two iron-sites (Fe2) form an antiferromagnetically coupled dimer whereas two Fe1 establish an antiferromagnetic intertetramer coupling. The effective magnetic exchange of the two magnetic sublattices is based on dominating Dzyaloshinskii-Moriya interaction due to the rare situation of canceling Heisenberg exchange interactions. According to our investigations, the ground states of the two polymorphs differ in terms of their Fe-site specific electric field gradients Vii. Contrary to the α-phase, a degenerate set of Vzz and Vyy for both iron sites in β-FeMoO4 is extracted from density functional theory calculations. In the vicinity of the phase transition (β → α), the degeneracy of the β-phase is lifted. Correspondingly, we observe a softening of the ν(Mo-O) phonon modes. Detailed Mössbauer spectra confirm the crosslike 90° antiferromagnetic structure for both modifications and solve the origin of the longstanding issue of disparate quadrupole splittings in α- and β-FeMoO4
ASJC Scopus subject areas
- Materials Science(all)
- Electronic, Optical and Magnetic Materials
- Energy(all)
- General Energy
- Chemistry(all)
- Physical and Theoretical Chemistry
- Materials Science(all)
- Surfaces, Coatings and Films
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In: Journal of Physical Chemistry C, Vol. 125, No. 10, 18.03.2021, p. 5947-5956.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - FeMoO4 revisited: Crosslike 90° noncollinear antiferromagnetic structure caused by dzyaloshinskii-moriya interaction
AU - Ksenofontov, V.
AU - Pashkevich, Yu G.
AU - Panthöfer, M.
AU - Gnezdilov, V.
AU - Babkin, R.
AU - Klauer, R.
AU - Lemmens, P.
AU - Möller, A.
N1 - Funding Information: This work received support from the German Science Foundation (DFG, INST 247/875-1, INST 247/991-1). A.M. and V.K. acknowledge funding from the Carl Zeiss Foundation. P.L. acknowledges support by DFG within DFG Le967/16-1 and EXC 2123 QuantumFrontiers (DFG / EXC 390837967).
PY - 2021/3/18
Y1 - 2021/3/18
N2 - The ground state of Fe2+ (S = 2) in α- and β-FeMoO4 is investigated by experiments including X-ray diffraction, Raman scattering, and 57Fe-Mössbauer spectroscopy below 300 K and evaluated by theoretical modeling. Both modifications crystallize in the space group C2/m with the same set of Wyckoff positions. The structural feature of α- and β-FeMoO4 is a tetramer of the so-called butterfly motif. Two iron-sites (Fe2) form an antiferromagnetically coupled dimer whereas two Fe1 establish an antiferromagnetic intertetramer coupling. The effective magnetic exchange of the two magnetic sublattices is based on dominating Dzyaloshinskii-Moriya interaction due to the rare situation of canceling Heisenberg exchange interactions. According to our investigations, the ground states of the two polymorphs differ in terms of their Fe-site specific electric field gradients Vii. Contrary to the α-phase, a degenerate set of Vzz and Vyy for both iron sites in β-FeMoO4 is extracted from density functional theory calculations. In the vicinity of the phase transition (β → α), the degeneracy of the β-phase is lifted. Correspondingly, we observe a softening of the ν(Mo-O) phonon modes. Detailed Mössbauer spectra confirm the crosslike 90° antiferromagnetic structure for both modifications and solve the origin of the longstanding issue of disparate quadrupole splittings in α- and β-FeMoO4
AB - The ground state of Fe2+ (S = 2) in α- and β-FeMoO4 is investigated by experiments including X-ray diffraction, Raman scattering, and 57Fe-Mössbauer spectroscopy below 300 K and evaluated by theoretical modeling. Both modifications crystallize in the space group C2/m with the same set of Wyckoff positions. The structural feature of α- and β-FeMoO4 is a tetramer of the so-called butterfly motif. Two iron-sites (Fe2) form an antiferromagnetically coupled dimer whereas two Fe1 establish an antiferromagnetic intertetramer coupling. The effective magnetic exchange of the two magnetic sublattices is based on dominating Dzyaloshinskii-Moriya interaction due to the rare situation of canceling Heisenberg exchange interactions. According to our investigations, the ground states of the two polymorphs differ in terms of their Fe-site specific electric field gradients Vii. Contrary to the α-phase, a degenerate set of Vzz and Vyy for both iron sites in β-FeMoO4 is extracted from density functional theory calculations. In the vicinity of the phase transition (β → α), the degeneracy of the β-phase is lifted. Correspondingly, we observe a softening of the ν(Mo-O) phonon modes. Detailed Mössbauer spectra confirm the crosslike 90° antiferromagnetic structure for both modifications and solve the origin of the longstanding issue of disparate quadrupole splittings in α- and β-FeMoO4
UR - http://www.scopus.com/inward/record.url?scp=85103446388&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcc.1c01134
DO - 10.1021/acs.jpcc.1c01134
M3 - Article
AN - SCOPUS:85103446388
VL - 125
SP - 5947
EP - 5956
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 10
ER -