963 research outputs found
Renormalization of the tunnel splitting in a rotating nanomagnet
We study spin tunneling in a magnetic nanoparticle with biaxial anisotropy
that is free to rotate about its anisotropy axis. Exact instanton of the
coupled equations of motion is found that connects degenerate classical energy
minima. We show that mechanical freedom of the particle renormalizes magnetic
anisotropy and increases the tunnel splitting.Comment: 4 pages, 3 figure
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
Electromechanical Magnetization Switching
We show that the magnetic moment of a composite multiferroic torsional
oscillator can be switched by the electric field. The 180 switching arises
from the spin-rotation coupling and is not prohibited by the different symmetry
of the magnetic moment and the electric field as in the case of a stationary
magnet. Analytical equations describing the system have been derived and
investigated numerically. Phase diagrams showing the range of parameters
required for the switching have been obtained.Comment: 7 pages, 5 figure
Self-organized patterns of macroscopic quantum tunneling in molecular magnets
We study low temperature resonant spin tunneling in molecular magnets induced
by a field sweep with account of dipole-dipole interactions. Numerical
simulations uncovered formation of self-organized patterns of the magnetization
and of the ensuing dipolar field that provide resonant condition inside a
finite volume of the crystal. This effect is robust with respect to disorder
and should be relevant to the dynamics of the magnetization steps observed in
molecular magnets.Comment: 4 Phys. Rev. pages, 5 figure
Excitation modes of vortices in sub-micron magnetic disks
Classical and quantum theory of spin waves in the vortex state of a
mesoscopic sub-micron magnetic disk has been developed with account of the
finite mass density of the vortex. Oscillations of the vortex core resemble
oscillations of a charged string in a potential well in the presence of the
magnetic field. Conventional gyroscopic frequency appears as a gap in the
spectrum of spin waves of the vortex. The mass of the vortex has been computed
that agrees with experimental findings. Finite vortex mass generates a
high-frequency branch of spin waves. Effects of the external magnetic field and
dissipation have been addressed.Comment: 12 page
- …