14,230 research outputs found
Magnetic double refraction in piezoelectrics
A new type of magneto-optical effect in piezoelectrics is predicted. A low
frequency behavior of Faraday effect is found.Comment: 2 pages, to be published in Europhys. Lett
Macroscopic quantum effects generated by the acoustic wave in a molecular magnet
We have shown that the size of the magnetization step due to resonant spin
tunneling in a molecular magnet can be strongly affected by sound. The
transverse acoustic wave can also generate macroscopic quantum beats of the
magnetization during the field sweep.Comment: 4 pages, 6 figure
Rotational Doppler Effect in Magnetic Resonance
We compute the shift in the frequency of the spin resonance in a solid that
rotates in the field of a circularly polarized electromagnetic wave. Electron
spin resonance, nuclear magnetic resonance, and ferromagnetic resonance are
considered. We show that contrary to the case of the rotating LC circuit, the
shift in the frequency of the spin resonance has strong dependence on the
symmetry of the receiver. The shift due to rotation occurs only when rotational
symmetry is broken by the anisotropy of the gyromagnetic tensor, by the shape
of the body, or by magnetocrystalline anisotropy. General expressions for the
resonance frequency and power absorption are derived and implications for
experiment are discussed.Comment: 8 pages, 4 figure
Vanishing bulk viscosities and conformal invariance of unitary Fermi gas
By requiring general-coordinate and conformal invariance of the hydrodynamic
equations, we show that the unitary Fermi gas has zero bulk viscosity, zeta=0,
in the normal phase. In the superfluid phase, two of the bulks viscosities have
to vanish, zeta_1=zeta_2=0, while the third one zeta_3 is allowed to be
nonzero.Comment: 4 page
Infra-Red Surface-Plasmon-Resonance technique for biological studies
We report on a Surface-Plasmon-Resonance (SPR) technique based on Fourier
-Transform - Infra - Red (FTIR) spectrometer. In contrast to the conventional
surface plasmon technique, operating at a fixed wavelength and a variable angle
of incidence, our setup allows the wavelength and the angle of incidence to be
varied simultaneously. We explored the potential of the SPR technique in the
infrared for biological studies involving aqueous solutions. Using computer
simulations, we found the optimal combination of parameters (incident angle,
wavelength) for performing this task. Our experiments with physiologically
important glucose concentrations in water and in human plasma verified our
computer simulations. Importantly, we demonstrated that the sensitivity of the
SPR technique in the infrared range is not lower and in fact is even higher
than that for visible light. We emphasize the advantages of infra red SPR for
studying glucose and other biological molecules in living cells.Comment: 8 pages,8 figure
Magnonic Crystal Theory of the Spin-Wave Frequency Gap in Low-Doped Manganites
A theory of three-dimensional (3D) hypothetical magnonic crystal (conceived
as the magnetic counterpart of the well-known photonic crystal) is developed
and applied to explain the existence of a spin-wave frequency gap recently
revealed in low-doped manganites by neutron scattering.
A successful confrontation with the experimental results allows us to formulate
a working hypothesis that certain manganites could be regarded as 3D magnonic
crystals existing in nature.Comment: 5 pages, 3 figures, submitted to PR
Impact parameter dependence of heavy ion e+ e- pair production to all orders in Z alpha
The heavy ion probability for continuum e+ e- pair production has been
calculated to all orders in Z alpha as a function of impact parameter. The
formula resulting from an exact solution of the semiclassical Dirac equation in
the ultrarelativistic limit is evaluated numerically. In a calculation of gamma
= 100 colliding Au ions the probability of e+ e- pair production is reduced
from the perturbation theory result throughout the impact parameter range.Comment: 20 pages, latex, revtex, 6 eps figures. Revised Phys. Rev. C version
with minor additions, one figure added, and added reference
Low energy excitations and singular contributions in the thermodynamics of clean Fermi liquids
Using a recently suggested method of bosonization in an arbitrary dimension,
we study the anomalous contribution of the low energy spin and charge
excitations to thermodynamic quantities of a two-dimensional (2D) Fermi liquid.
The method is slightly modified for the present purpose such that the effective
supersymmetric action no longer contains the high energy degrees of freedom but
still accounts for effects of the finite curvature of the Fermi surface.
Calculating the anomalous contribution to the specific heat, we
show that the leading logarithmic in temperature corrections to can be obtained in a scheme combining a summation of ladder diagrams
and renormalization group equations. The final result is represented as the sum
of two separate terms that can be interpreted as coming from singlet and
triplet superconducting excitations. The latter may diverge in certain regions
of the coupling constants, which should correspond to the formation of triplet
Cooper pairs.Comment: 29 pages, 13 figure
Incomplete Photonic Bandgap as Inferred from the Speckle Pattern of Scattered Light Waves
Motivated by recent experiments on intensity correlations of the waves
transmitted through disordered media, we demonstrate that the speckle pattern
from disordered photonic crystal with incomplete band-gap represents a
sensitive tool for determination the stop-band width. We establish the
quantitative relation between this width and the {\em angualar anisotropy} of
the intensity correlation function.Comment: 6 pages, 3 figure
Measuring nonadiabaticity of molecular quantum dynamics with quantum fidelity and with its efficient semiclassical approximation
We propose to measure nonadiabaticity of molecular quantum dynamics
rigorously with the quantum fidelity between the Born-Oppenheimer and fully
nonadiabatic dynamics. It is shown that this measure of nonadiabaticity applies
in situations where other criteria, such as the energy gap criterion or the
extent of population transfer, fail. We further propose to estimate this
quantum fidelity efficiently with a generalization of the dephasing
representation to multiple surfaces. Two variants of the multiple-surface
dephasing representation (MSDR) are introduced, in which the nuclei are
propagated either with the fewest-switches surface hopping (FSSH) or with the
locally mean field dynamics (LMFD). The LMFD can be interpreted as the
Ehrenfest dynamics of an ensemble of nuclear trajectories, and has been used
previously in the nonadiabatic semiclassical initial value representation. In
addition to propagating an ensemble of classical trajectories, the MSDR
requires evaluating nonadiabatic couplings and solving the Schr\"{o}dinger (or
more generally, the quantum Liouville-von Neumann) equation for a single
discrete degree of freedom. The MSDR can be also used to measure the importance
of other terms present in the molecular Hamiltonian, such as diabatic
couplings, spin-orbit couplings, or couplings to external fields, and to
evaluate the accuracy of quantum dynamics with an approximate nonadiabatic
Hamiltonian. The method is tested on three model problems introduced by Tully,
on a two-surface model of dissociation of NaI, and a three-surface model
including spin-orbit interactions. An example is presented that demonstrates
the importance of often-neglected second-order nonadiabatic couplings.Comment: 14 pages, 4 figures, submitted to J. Chem. Phy
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