Magnetoelectric and magnetoelastic properties of rare-earth ferroborates

Abstract

The magnetic, electric, magnetoelectric, and magnetoelastic properties of rare-earth ferroborates RFe3(BO3)4 (R=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er) as well as yttrium ferroborate YFe3(BO3)4 have been studied comprehensively. A strong dependence not only of the magnetic but also magnetoelectric properties on the type of rare-earth ion, specifically, on its anisotropy, which determines the magnetic structure and the large contribution to the electric polarization, has been found. This is manifested in the strong temperature dependence of the polarization below the Néel point TN and its specific field dependence, which is determined by the competition between the external and exchange f-d fields. A close correlation has been found between the magnetoelastic properties of ferroborates and the magnetoelastic and magnetic anomalies at magnetic-field induced phase transitions. It is found that in easy-plane ferroborates, together with magnetic-field induced electric polarization spontaneous polarization also arises below the Néel point. The ferroelectric ordering in ferroborates is of extrinsic character, giving rise to strong magnetoelectric coupling below TN. Aside from the antiferromagnetic phase transition, the particulars of the structural phase transition accompanied by anomalies of the dielectric and magnetoelectric properties are examined for the first time. The character of the dielectric anomalies at a structural transition is analyzed for the first time on the basis of Landau’s approach.

Low-temperature absorption spectra and electron structure of HoFe3(BO3)4 single crystal

“…Investigation of magnetic and magnetoelectric properties of the HoFe 3 (BO 3 ) 4 single crystal showed that it also refers to multiferroics [4][5][6]. In this crystal the considerable electric polarization in magnetic field [6], the giant magnetodielectric effect and the spontaneous polarization in the region of magnetic ordering [4] were found.…”

“…Number and polarizations of lines in this band correspond to the splitting in the D 3 symmetry according to (5), (10) (Fig. 11).…”

“…A number of the rare-earth ferroborates with the common formula RFe 3 (BO 3 ) 4 (where R is the rare-earth element) belong to the class of multiferroics -the materials which possess the interrelated magnetic, electric and elastic ordering (see, e.g., [1][2][3][4][5][6][7]). In recent years these compounds attract a growing interest in view of their manifold potential applications.…”

Ho and Fe magnetic ordering in multiferroic HoFe3(BO3)4

“…2,3 However, recent observations of improper ferroelectricity, 4,5 anomalous even within the realm of magnetoelectricity, require an even better understanding of the subject. Rare earth iron borates RFe 3 (BO 3 ) 4 , where R = rare earth, [6][7][8][9] are multiferroics, characterized by long-range magnetic wave vectors q c*, [10][11][12][13][14][15] and show a large magnetoelectric effect ( P ∼ 100 μC m −2 ). The RFe 3 (BO 3 ) 4 crystal structure 16,17 allows a dominant Fe-Fe exchange interaction, which is reflected by a T N in a narrow temperature range (30-40 K) for compounds with different R. The rare earth exchange interaction takes place via O and B, i.e., R-O-B-O-R.…”

Switching of Magnons by Electric and Magnetic Fields in Multiferroic Borates

“…Rare-earth iron-borates represent one exotic class of multiferroics [46][47][48]. At high temperatures, all rareearth borates reveal a non-centrosymmetric trigonal structure belonging to the space group R32 [49][50][51][52] which persist down to lowest temperatures for Sm-and Nd-ironborates [53].…”