Nonresonant x-ray magnetic scattering on rare-earth iron boratesRFe3(BO3)4

Abstract

Hard x-ray scattering experiments with a photon energy of 100 keV were performed as a function of temperature and applied magnetic field on selected compounds of the RFe 3 ͑BO 3 ͒ 4 family. The results show the presence of several diffraction features, in particular, nonresonant magnetic reflections in the magnetically ordered phase and structural reflections that violate the diffraction conditions for the low-temperature phase P3 1 21 of the rare-earth iron borates. The temperature and field dependence of the magnetic superlattice reflections corroborate the magnetic structures of the borate compounds obtained by neutron diffraction. The detailed analysis of the intensity and scattering cross section of the magnetic reflection reveals details of the magnetic structure of these materials such as the spin domain structure of NdFe 3 ͑BO 3 ͒ 4 and GdFe 3 ͑BO 3 ͒ 4 . Furthermore we find that the correlation length of the magnetic domains is around 100 Å for all the compounds and that the Fe moments are rotated 53°Ϯ 3°off from the hexagonal basal plane in GdFe 3 ͑BO 3 ͒ 4 .

Control of coexisting magnetic phases by electric fields inNdFe3(BO3)4

“…It was also shown earlier that a magnetic field of 2 T applied to the CM phase suffices to create a mono-domain CM-B state [17,18]. Our analysis of the Stokes scans yields the same result, using a different and independent method.…”

“…This strong magnetoelectric coupling sparked significant interest in NdFe 3 (BO 3 ) 4 and immediately raised the question about its microscopic origin. Recent x-ray diffraction experiments already provided microscopic insight and implied that the finite P a is related to the magnetic field-induced CM order [17,18]. In principle, the strong magnetoelectric coupling discovered in previous studies should also enable to alter the magnetic order of NdFe 3 (BO 3 ) 4 by applying external electric fields.…”

Lattice dynamics and a magnetic-structural phase transition in the nickel orthoborateNi3(BO3)2Pisarev1, Prosnikov2, Davydov3 et al. 2016Phys. Rev. B221100View full textAdd to dashboardCite

“…It is worth mentioning, however, that conventional x-ray and neutron diffraction experiments in many cases fail to detect small atomic displacements. For example, it has recently been demonstrated for the rare-earth (R) iron oxyborates RFe3(BO3)4, using hard x-ray scattering technique [70].…”

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

“…Concerning the x-ray scattering measurements on these compounds, until now, it has not been possible to directly determine the magnetic anisotropy of the rare earth, as the measured intensity variation as a function of the azimuthal angle about the scattering vector is flat. 10,11 Also resonant soft x-ray scattering measurements at the Fe L 2,3 absorption edges, which in principle could directly probe the Fe magnetic anisotropy, are not possible, as already the lowest indexed magnetic reflection (0 0 1.5) in these compounds is not accessible at these energies.…”

“…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.…”