Mossbauer Study of the Modulated Magnetic Structure of FeV[O.sub.4]

• Published in: Journal of experimental and theoretical physics 2017-06, Vol.124 (6), p.943
• Main Authors: Sobolev, A.V, Presnyakov, I.A, Rusakov, V.S, Gapochka, A.M, Glazkova, Ya.S, Matsnev, M.E, Pankratov, D.A
• Format: Article
• Language: English
• Subjects: Analysis; Electric fields; Ferroalloys; Magnetism
• ISSN: 1063-7761; 1090-6509
• DOI: 10.1134/S1063776117060164

Mossbauer spectroscopy is used to study the FeV[O.sub.4] multiferroic, which undergoes two magnetic phase transitions at [T.sub.N1] ~ 22 K and [T.sub.N2] ~ 15 K. The first transition ([T.sub.N1]) is related to transformation from a paramagnetic state into a magnetically ordered state of a spin density wave, and the second transition ([T.sub.N2]) is associated with a change in the type of the spatial magnetic structure of the vanadate. The electric field gradient tensor at [sup.57]Fe nuclei is calculated to perform a crystal-chemical identification of the partial Mossbauer spectra corresponding to various crystallographic positions of [Fe.sup.3+] cations. The spectra measured in the range [T.sub.N2] < T < [T.sub.N1] are analyzed on the assumption about amplitude modulation of the magnetic moments of iron atoms [[mu].sub.Fe]. The results of model intersection of the spectra recorded at T < [T.sub.N2] point to a high degree of anharmonicity of the helicoidal magnetic structure of the vanadate and to elliptic polarization of [[mu].sub.Fe]. These features are characteristic of type-II multiferroics. The temperature dependences of the hyperfine interaction parameters of [sup.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.