44 research outputs found
Magnetic structure of the field-induced multiferroic GdFe3(BO3)4
We report a magnetic x-ray scattering study of the field-induced multiferroic
GdFe3(BO3)4. Resonant x-ray magnetic scattering at the Gd LII,III edges
indicates that the Gd moments order at TN ~ 37 K. The magnetic structure is
incommensurate below TN, with the incommensurability decreasing monotonically
with decreasing temperature until a transition to a commensurate magnetic phase
is observed at T ~ 10 K. Both the Gd and Fe moments undergo a spin
reorientation transition at TSR ~ 9 K such that the moments are oriented along
the crystallographic c axis at low temperatures. With magnetic field applied
along the a axis, our measurements suggest that the field-induced polarization
phase has a commensurate magnetic structure with Gd moments rotated ~45 degrees
toward the basal plane, which is similar to the magnetic structure of the Gd
subsystem observed in zero field between 9 and 10 K, and the Fe subsystem has a
ferromagnetic component in the basal plane.Comment: 27 pages, 7 figures, to appear in Phys. Rev.
Magnetic and thermodynamic properties and spin-flop-driven magnetodielectric response of the antiferromagnetic Pb2Fe2Ge2O9 single crystals
ANTIFERROMAGNETIC RESONANCE IN CRYSTALS OF THE FAMILY PrXY1-XFe3(BO3)4 WITH ANGULAR MAGNETIC STRUCTURE
With diamagnetic dilution of the PrFe3(BO3)4 subsystem with nonmagnetic yttrium, the anisotropic contribution of the Pr3+ subsystem decreases; in the concentration range x = 0.67-0.45, a transition from the LO to the LP magnetic structure occurs through the formation of angular magnetic structure
Magnetoelectric Effect and Spontaneous Polarization in HoFe(BO) and HoNdFe(BO)
The thermodynamic, magnetic, dielectric, and magnetoelectric properties of
HoFe(BO) and HoNdFe(BO) are
investigated. Both compounds show a second order Ne\'{e}l transition above 30 K
and a first order spin reorientation transition below 10 K.
HoFe(BO) develops a spontaneous electrical polarization below the
Ne\'{e}l temperature (T) which is diminished in external magnetic fields.
No magnetoelectric effect could be observed in HoFe(BO). In
contrast, the solid solution HoNdFe(BO) exhibits
both, a spontaneous polarization below T and a magnetoelectric effect at
higher fields that extends to high temperatures. The superposition of
spontaneous polarization, induced by the internal magnetic field in the ordered
state, and the magnetoelectric polarizations due to the external field results
in a complex behavior of the total polarization measured as a function of
temperature and field.Comment: 12 pages, 15 figure
Subterahertz and terahertz spin and lattice dynamics of the insulating ferromagnet PbMnBO4
Magnetic resonance studies of mixed chalcospinel CuCr2SxSe4−x (x = 0; 2) and CoxCu1−xCr2S4 (x = 0.1; 0.2) nanocrystals with strong interparticle interactions
Magnetic resonance characteristics of mixed chalcospinel nanocrystals CuCr2SxSe4−x (x = 0 and 2) and CoxCu1−xCr2S4 (x = 0.1 and 0.2) have been investigated. It has been established based on TEM, SEM and resonance data that all the samples contain both blocks with sizes from 1 to 50 m of compacted nanosized crystallites and individual nanoparticles with sizes from 10 to 30 nm. The studies provide evidence of strong interparticle interaction in all the samples leading to high values of the blocking temperature. Magnetic dipolar field arise in the boundary regions of interacting adjacent nanocrystals below the blocking temperature. This results in inhomogeneous broadening of the magnetic resonance spectrum along with appearance of additional absorption lines. With increase in magnetic anisotropy at low temperatures, a shift of the resonance field along with line broadening are observed for all the studied compounds due to freezing of the moments in the nanoparticles, both in the individual and compacted ones. A gapped characteristic of the resonance spectrum is established below the freezing temperature Tfr, with the energy gap defined by the averaged magnetic anisotropy . Anionic substitution of sulfur by selenium results in a decrease in the magnetic anisotropy. In contrast, cationic substitution of copper by cobalt increases the magnetic anisotropy due to a strong contribution from the latter ion