4,373 research outputs found
Hydrostatic pressure to trigger and assist magnetic transitions: baromagnetic refrigeration
The possible application of the barocaloric effect to produce solid state
refrigerators is a topic of interest in the field of applied physics. In this
work, we present experimental data about the influence of external pressure on
the magnetic properties of a manganite with phase separation. Using the Jahn
Teller effect associated with the presence of the charge ordering we were able
to follow the transition to the ferromagnetic state induced by pressure. We
also demonstrated that external pressure can assist the ferromagnetic state,
decreasing the magnetic field necessary to generate the magnetic transition.Comment: Acepted to be published in Applied Physics Letter
Simultaneous electric and magnetic field induced nonvolatile memory
We investigate the electric field induced resistive switching effect and
magnetic field induced fraction enlargement on a polycrystalline sample of a
colossal magnetoresistive compound displaying intrinsic phase coexistence. Our
data show that the electric effect (presumably related to the presence of
inhomogeinities) is present in a broad temperature range(300 to 20 K), being
observable even in a mostly homogeneous ferromagnetic state. In the temperature
range in which low magnetic field determines the phase coexistence fraction,
both effects, though related to different mechanisms, are found to determine
multilevel nonvolatile memory capabilities simultaneously.Comment: Submited to AP
Reply to Comment on "Existence of Internal Modes of sine-Gordon Kinks"
In this reply to the comment by C. R. Willis, we show, by quoting his own
statements, that the simulations reported in his original work with Boesch
[Phys. Rev. B 42, 2290 (1990)] were done for kinks with nonzero initial
velocity, in contrast to what Willis claims in his comment. We further show
that his alleged proof, which assumes among other approximations that kinks are
initially at rest, is not rigorous but an approximation. Moreover, there are
other serious misconceptions which we discuss in our reply. As a consequence,
our result that quasimodes do not exist in the sG equation [Phys. Rev. E 62,
R60 (2000)] remains true.Comment: Reply to a comment by C. R. Willis on Phys. Rev. E 62, R60 (2000), to
appear in Physical Review
Anomalies of ac driven solitary waves with internal modes: Nonparametric resonances induced by parametric forces
We study the dynamics of kinks in the model subjected to a
parametric ac force, both with and without damping, as a paradigm of solitary
waves with internal modes. By using a collective coordinate approach, we find
that the parametric force has a non-parametric effect on the kink motion.
Specifically, we find that the internal mode leads to a resonance for
frequencies of the parametric driving close to its own frequency, in which case
the energy of the system grows as well as the width of the kink. These
predictions of the collective coordinate theory are verified by numerical
simulations of the full partial differential equation. We finally compare this
kind of resonance with that obtained for non-parametric ac forces and conclude
that the effect of ac drivings on solitary waves with internal modes is exactly
the opposite of their character in the partial differential equation.Comment: To appear in Phys Rev
Coupled magnetic and elastic properties in LaPr(CaSr)MnO manganites
We investigate a series of manganese oxides, the
La0.225Pr0.4(Ca1-xSrx)0.375MnO3 system. The x = 0 sample is a prototype
compound for the study of phase separation in manganites, where ferromagnetic
and charge ordered antiferromagnetic phases coexist. Replacing Ca2+ by Sr2+
gradually turns the system into a homogeneous ferromagnet. Our results show
that the material structure plays a major role in the observed magnetic
properties. On cooling, at temperatures below 100 K, a strong contraction of
the lattice is followed by an increase in the magnetization. This is observed
both through thermal expansion and magnetostriction measurements, providing
distinct evidence of magneto-elastic coupling in these phase separated
compounds
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