303 research outputs found
Magnetic and electric properties in the distorted tetrahedral spin chain system Cu3Mo2O9
We study the multiferroic properties in the distorted tetrahedral quasi-one
dimensional spin system CuMoO, in which the effects of the low
dimensionality and the magnetic frustration are expected to appear
simultaneously. We clarify that the antiferromagnetic order is formed together
with ferroelectric properties at K under zero magnetic field
and obtain the magnetic-field-temperature phase diagram by measuring dielectric
constant and spontaneous electric polarization. It is found that the
antiferromagnetic phase possesses a spontaneous electric polarization parallel
to the c axis when the magnetic field is applied parallel to the a axis. On
the other hand, there are three different ferroelectric phases in the
antiferromagnetic phase for parallel to the c axis.Comment: 4 pages, 3 figures, LT26 proceedings, accepted for publication in J.
Phys.: Conf. Se
Longitudinal magnetic excitation in KCuCl3 studied by Raman scattering under hydrostatic pressures
We measure Raman scattering in an interacting spin-dimer system KCuCl3 under
hydrostatic pressures up to 5 GPa mediated by He gas. In the pressure-induced
quantum phase, we observe a one-magnon Raman peak, which originates from the
longitudinal magnetic excitationand is observable through the second-order
exchange interaction Raman process. We report the pressure dependence of the
frequency, halfwidth and Raman intensity of this mode.Comment: 4 pages, 3 figures, inpress in JPCS as a proceeding of LT2
Magnetic field-induced one-magnon Raman scattering in the magnon Bose-Einstein condensation phase of TlCuCl
We report the observation of the -symmetric one-magnon Raman peak
in the magnon Bose-Einstein condensation phase of TlCuCl. Its Raman shift
traces the one-magnon energy at the magnetic point, and its intensity
is proportional to the squared transverse magnetization. The appearance of the
one-magnon Raman scattering originates from the exchange magnon Raman process
and reflects the change of the magnetic-state symmetry. Using the bond-operator
representation, we theoretically clarify the Raman selection rules, being
consistent with the experimental results.Comment: 6 pages, 4 figure
Successive phase transitions to antiferromagnetic and weak-ferromagnetic long-range orders in quasi-one-dimensional antiferromagnet CuMoO
Investigation of the magnetism of CuMoO single crystal, which has
antiferromagnetic (AF) linear chains interacting with AF dimers, reveals an AF
second-order phase transition at K. Although weak
ferromagnetic-like behavior appears at lower temperatures in low magnetic
fields, complete remanent magnetization cannot be detected down to 0.5 K.
However, a jump is observed in the magnetization below weak ferromagnetic (WF)
phase transition at K when a tiny magnetic field along
the a axis is reversed, suggesting that the coercive force is very weak. A
component of magnetic moment parallel to the chain forms AF long-range order
(LRO) below , while a perpendicular component is disordered above
at zero magnetic field and forms WF-LRO below .
Moreover, the WF-LRO is also realized with applying magnetic fields even
between and . These results are explainable by both
magnetic frustration among symmetric exchange interactions and competition
between symmetric and asymmetric Dzyaloshinskii-Moriya exchange interactions.Comment: 7 pages, 7 figure
Spin fluctuations in CuGeO probed by light scattering
We have measured temperature dependence of low-frequency Raman spectra in
CuGeO, and have observed the quasi-elastic scattering in the
polarization above the spin-Peierls transition temperature. We attribute it to
the fluctuations of energy density in the spin system. The magnetic specific
heat and an inverse of the magnetic correlation length can be derived from the
quasi-elastic scattering. The inverse of the magnetic correlation length is
proportional to at high temperatures. We compare the
specific heat with a competing- model. This model cannot explain
quantitatively both the specific heat and the magnetic susceptibility with the
same parameters. The origin of this discrepancy is discussed.Comment: 17 pages, REVTeX, 5 Postscript figures; in press in PR
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