4,955 research outputs found
Power law velocity fluctuations due to inelastic collisions in numerically simulated vibrated bed of powder}
Distribution functions of relative velocities among particles in a vibrated
bed of powder are studied both numerically and theoretically. In the solid
phase where granular particles remain near their local stable states, the
probability distribution is Gaussian. On the other hand, in the fluidized
phase, where the particles can exchange their positions, the distribution
clearly deviates from Gaussian. This is interpreted with two analogies;
aggregation processes and soft-to-hard turbulence transition in thermal
convection. The non-Gaussian distribution is well-approximated by the
t-distribution which is derived theoretically by considering the effect of
clustering by inelastic collisions in the former analogy.Comment: 7 pages, using REVTEX (Figures are inculded in text body)
%%%Replacement due to rivision (Europhys. Lett., in press)%%
Specific heat study of spin-structural change in pyrochlore NdMoO
By measurements of specific heat, we have investigated the magnetic field
() induced spin-structural change in NdMoO that shows
spin-chirality-related magneto-transport phenomena. A broad peak around 2 K
caused by the ordering of 2-in 2-out structure of the Nd moments at zero
shifts to the lower temperature () up to around 3 T and then to the higher
above around 3 T with increasing for all the direction of . This is
due to the crossover from antiferromagnetic to ferromagnetic arrangement
between the Nd and Mo moments. While the peak increases monotonically above
3 T for //[100], another peak emerges around 0.9 K at 12 T for //[111],
which is ascribed to the ordering of 3-in 1-out structure. For //[110], a
spike like peak is observed at around 3 T, which is caused perhaps by some spin
flip transition.Comment: 5 pages, 4 figure
Perovskite Manganites Hosting Versatile Multiferroic Phases with Symmetric and Antisymmetric Exchange Strictions
Complete magnetoelectric (ME) phase diagrams of orthorhombic MnO
with and without magnetic moments on the ions have been established. Three
kinds of multiferroic ground states, the -cycloidal, the -cycloidal,
and the collinear -type phases, have been identified by the distinct ME
responses. The electric polarization of the -type phase dominated by the
symmetric spin exchange () is more than 10 times as
large as that of the -cycloidal phase dominated by the antisymmetric one
(), and the ME response is enhanced near the
bicritical phase boundary between these multiferroic phases of different
origins. These findings will provide an important clue for the development of
the magnetically induced multiferroics.Comment: 5 pages, 3 figure
- …