Mössbauer study of the modulated magnetic structure of FeVO4

• Published in: Journal of experimental and theoretical physics Vol. 124; no. 6; pp. 943 - 956
• Main Authors: Sobolev, A. V., Presnyakov, I. A., Rusakov, V. S., Gapochka, A. M., Glazkova, Ya. S., Matsnev, M. E., Pankratov, D. A.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-06-2017; Springer Nature B.V
• Subjects: Amplitude modulation; Anharmonicity; Cations; Classical and Quantum Gravitation; Crystallography; Disorder; Elementary Particles; Interaction parameters; Iron; Magnetic structure; Magnetism; Molecular structure; Multiferroic materials; Nuclei; Order; Particle and Nuclear Physics; Phase Transition in Condensed System; Phase transitions; Physics; Physics and Astronomy; Polarization; Quantum Field Theory; Relativity Theory; Solid State Physics; Spectra; Spectroscopic analysis; Spectrum analysis
• ISSN: 1063-7761; 1090-6509
• DOI: 10.1134/S1063776117060164

Mössbauer spectroscopy is used to study the FeVO
4
multiferroic, which undergoes two magnetic phase transitions at
T
N
1
≈ 22 K and
T
N
2
≈ 15 K. The first transition (
T
N
1
) is related to transformation from a paramagnetic state into a magnetically ordered state of a spin density wave, and the second transition (
T
N
2
) is associated with a change in the type of the spatial magnetic structure of the vanadate. The electric field gradient tensor at
57
Fe nuclei is calculated to perform a crystal-chemical identification of the partial Mössbauer spectra corresponding to various crystallographic positions of Fe
3+
cations. The spectra measured in the range
T
N
2
<
T
<
T
N
1
are analyzed on the assumption about amplitude modulation of the magnetic moments of iron atoms μ
Fe
. The results of model intersection of the spectra recorded at
T
<
T
N
2
point to a high degree of anharmonicity of the helicoidal magnetic structure of the vanadate and to elliptic polarization of μ
Fe
. These features are characteristic of type-II multiferroics. The temperature dependences of the hyperfine interaction parameters of
57
Fe nuclei that were obtained in this work are analyzed in terms of the Weiss molecular field model on the assumption of orbital contribution to the magnetic moments of iron cations.