99 research outputs found
Magnetoelectricity and Magnetostriction due to the Rare Earth Moment in TmAl(BO)
The magnetic properties, the magnetostriction, and the magnetoelectric effect
in the d-electron free rare-earth aluminum borate TmAl(BO) are
investigated between room temperature and 2 K. The magnetic susceptibility
reveals a strong anisotropy with the hexagonal c-axis as the hard magnetic
axis. Magnetostriction measurements show a large effect of an in-plane field
reducing both, the a- and c-axis lattice parameters. The magnetoelectric
polarization change in a- and c-directions reaches up to 300 C/m at 70
kOe with the field applied along the a-axis. The magnetoelectric polarization
is proportional to the lattice contraction in magnetic field. The results of
this investigation prove the existence of a significant coupling between the
rare earth magnetic moment and the lattice in Al(BO) compounds
( = rare earth). They further show that the rare earth moment itself will
generate a large magnetoelectric effect which makes it easier to study and to
understand the origin of the magnetoelectric interaction in this class of
materials.Comment: 4 pages, 5 figure
Evidence for differentiation in the iron-helicoidal-chain in GdFe(BO)
We report on a single-crystal X-ray structure study of
at room temperature and at T=90 K. At room temperature
crystallizes in a trigonal space group R32 (No. 155), the same as found for
other members of iron-borate family . At 90 K the
structure of has transformed to the space group
(No. 152). The low-temperature structure determination gives new
insight into the weakly first-order structural phase transition at 156 K and
into the related Raman phonon anomalies. The discovery of two inequivalent iron
chains in the low temperature structure provide new point of view on the
low-temperature magnetic properties.Comment: Subm. to Acta Cryst.
Magnetization and specific heat of TbFe3(BO3)4: Experiment and crystal field calculations
We have studied the thermodynamic properties of single-crystalline
TbFe3(BO3)4. Magnetization measurements have been carried out as a function of
magnetic field (up to 50 T) and temperature up to 350K with the magnetic field
both parallel and perpendicular to the trigonal c-axis of the crystal. The
specific heat has been measured in the temperature range 2-300K with a magnetic
field up to 9 T applied parallel to the c-axis. The data indicate a structural
phase transition at 192 K and antiferromagnetic spin ordering at 40 K. A
Schottky anomaly is present in the specific heat data around 20 K, arising due
to two low-lying energy levels of the Tb3+ ions being split by f-d coupling.
Below TN magnetic fields parallel to the c-axis drive a spin-flop phase
transition, which is associated with a large magnetization jump. The highly
anisotropic character of the magnetic susceptibility is ascribed mainly to the
Ising-like behavior of the Tb3+ ions in the trigonal crystal field. We describe
our results in the framework of an unified approach which is based on
mean-field approximation and crystal-field calculations.Comment: 10 pages, 10 figures, 20 references, accepted by Phys. Rev.
Bifurcations observed in the spectra of coupled electron-phonon modes in multiferroic subjected to a magnetic field
We report on bifurcations effect mediated by the electron-phonon coupling in
a concentrated rare-earth-containing antiferromagnet, observed in the spectra
of coupled -electron-phonon modes under the influence of an external
magnetic field. The effect was observed in the low-temperature far-infrared
(terahertz) reflection spectra of a multiferroic easy-axis antiferromagnet
in magnetic fields . Both paramagnetic
and magnetically ordered phases (including a spin-flop one) were studied in
magnetic fields up to 30 T. We show that the field behavior of the coupled
modes can be successfully explained and modeled on the base of the equation
derived in the frame of the theory of coupled electron-phonon modes, with the
same field-independent electron-phonon interaction constant .Comment: 5 pages, 4 figure
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