1,269 research outputs found
Dynamical frictional phenomena in an incommensurate two-chain model
Dynamical frictional phenomena are studied theoretically in a two-chain model
with incommensurate structure. A perturbation theory with respect to the
interchain interaction reveals the contributions from phonons excited in each
chain to the kinetic frictional force. The validity of the theory is verified
in the case of weak interaction by comparing with numerical simulation. The
velocity and the interchain interaction dependences of the lattice structure
are also investigated. It is shown that peculiar breaking of analyticity states
appear, which is characteristic to the two-chain model. The range of the
parameters in which the two-chain model is reduced to the Frenkel-Kontorova
model is also discussed.Comment: RevTex, 9 pages, 7 PostScript figures, to appear in Phys. Rev.
Friction, order, and transverse pinning of a two-dimensional elastic lattice under periodic and impurity potentials
Frictional phenomena of two-dimensional elastic lattices are studied
numerically based on a two-dimensional Frenkel-Kontorova model with impurities.
It is shown that impurities can assist the depinning. We also investigate
anisotropic ordering and transverse pinning effects of sliding lattices, which
are characteristic of the moving Bragg glass state and/or transverse glass
state. Peculiar velocity dependence of the transverse pinning is observed in
the presence of both periodic and random potentials and discussed in the
relation with growing order and discommensurate structures.Comment: RevTeX, 4 pages, 5 figures. to appear in Phys. Rev. B Rapid Commu
Microstructural Change and Mechanical Property of Neutron Irradiated Ti-Ni Shape Memory Alloy
Microstructural change and mechanical property of Ti-Ni shape memory alloy after neutron irradiation have been studied. The neutron doses were from 1.4×10^ to 1.2×10^n/cm^2, and the irradiation temperature was under 423K. A halo ring was observed after the irradiation of 1.2×10^n/cm^2, which means that amorphous phase was induced by the neutron irradiation. In stress-strain curve, the critical point (σ_M) increased as the dose increased. At the highest dose, the stress-strain curve lost pseudoelasticity. These results indicate that such mechanical properties strongly depend on the amorphous formation
Effect of Local Inhomogeneity on Nucleation; Case of Charge Density Wave Depinning
The spatial inhomogeneities are expected to affect nucleation process in an
essential way. These effects are studied theoretically by considering the case
of the depinning of the charge density wave as a typical example. The threshold
field of the depinning of the one-dimensional commensurate charge density wave
with one impurity has been examined classically based on the phase Hamiltonian
at absolute zero. It is found that the threshold field is lowered by a finite
amount compared to that in the absence of an impurity.Comment: pages 12, LaTeX, 9 figures, uses jpsj.sty, submitted to J. Phys. Soc.
Jp
Anomalous pinning behavior in an incommensurate two-chain model of friction
Pinning phenomena in an incommensurate two-chain model of friction are
studied numerically. The pinning effect due to the breaking of analyticity
exists in the present model. The pinning behavior is, however, quite different
from that for the breaking of analyticity state of the Frenkel-Kontorova model.
When the elasticity of chains or the strength of interchain interaction is
changed, pinning force and maximum static frictional force show anomalously
complicated behavior accompanied by a successive phase transition and they
vanish completely under certain conditions.Comment: RevTex, 9 pages, 19 figures, to appear in Phys. Rev. B58 No.23(1998
Anomalous pressure effect on the remanent lattice striction of a (La,Pr)SrMnO bilayered manganite single crystal
We have studied the pressure effect on magnetostriction, both in the
-plane and along the c-axis, of a (La,Pr)SrMnO
bilayered manganite single crystal over the temperature region where the
field-induced ferromagnetic metal (FMM) transition takes place. For comparison,
we have also examined the pressure dependence of magnetization curves at the
corresponding temperatures. The applied pressure reduces the critical field of
the FMM transition and it enhances the remanent magnetostriction. An anomalous
pressure effect on the remanent lattice relaxation is observed and is similar
to the pressure effect on the remanent magnetization along the c-axis. These
findings are understood from the view point that the double-exchange
interaction driven FMM state is strengthened by application of pressure.Comment: 7 pages,7 figure
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