1,187 research outputs found
Spin-orbit field switching of magnetization in ferromagnetic films with perpendicular anisotropy
As an alternative to conventional magnetic field, the effective spin-orbit
field in transition metals, derived from the Rashba field experienced by
itinerant electrons confined in a spatial inversion asymmetric plane through
the s-d exchange interaction, is proposed for the manipulation of
magnetization. Magnetization switching in ferromagnetic thin films with
perpendicular magnetocrystalline anisotropy can be achieved by current induced
spin-orbit field, with small in-plane applied magnetic field. Spin-orbit field
induced by current pulses as short as 10 ps can initiate ultrafast
magnetization switching effectively, with experimentally achievable current
densities. The whole switching process completes in about 100 ps.Comment: 4 pages, 3 figure
Spin-Orbit Coupling and Tunneling Current in a Parabolic Quantum Dot
We propose a novel approach to explore the properties of a quantum dot in the
presence of the spin-orbit interaction and in a tilted magnetic field. The
spin-orbit coupling within the quantum dot manifest itself as anti-crossing of
the energy levels when the tilt angle is varied. The anti-crossing gap has a
non-monotonic dependence on the magnitude of the magnetic field and exhibits a
peak at some finite values of the magnetic field. From the dependence of the
tunneling current through the quantum dot on the bias voltage and the tilt
angle, the anti-crossing gap and most importantly the spin-orbit strength can
be uniquely determined
Massive Spin Collective Mode in Quantum Hall Ferromagnet
It is shown that the collective spin rotation of a single Skyrmion in quantum
Hall ferromagnet can be regarded as precession of the entire spin texture in
the external magnetic field, with an effective moment of inertia which becomes
infinite in the zero g-factor limit. This low-lying spin excitation may
dramatically enhance the nuclear spin relaxation rate via the hyperfine
interaction in the quantum well slightly away from filling factor equal one.Comment: 4 page
Turbulence in Binary Bose-Einstein Condensates Generated by Highly Non-Linear Rayleigh-Taylor and Kelvin-Helmholtz Instabilities
Quantum turbulence (QT) generated by the Rayleigh-Taylor instability in
binary immiscible ultracold 87Rb atoms at zero temperature is studied
theoretically. We show that the quantum vortex tangle is qualitatively
different from previously considered superfluids, which reveals deep relations
between QT and classical turbulence. The present QT may be generated at
arbitrarily small Mach numbers, which is a unique property not found in
previously studied superfluids. By numerical solution of the coupled
Gross-Pitaevskii equations we find that the Kolmogorov scaling law holds for
the incompressible kinetic energy. We demonstrate that the phenomenon may be
observed in the laboratory.Comment: Revised version. 7 pages, 8 figure
Observation of exchange Coulomb interactions in the quantum Hall state at nu=3
Coulomb exchange interactions of electrons in the nu=3 quantum Hall state are
determined from two inter-Landau level spin-flip excitations measured by
resonant inelastic light scattering. The two coupled collective excitations are
linked to inter-Landau level spin-flip transitions arising from the N=0 and N=1
Landau levels. The strong repulsion between the two spin-flip modes in the
long-wave limit is clearly manifested in spectra displaying Coulomb exchange
contributions that are comparable to the exchange energy for the quantum Hall
state at nu=1. Theoretical calculations within the Hartree-Fock approximation
are in a good agreement with measured energies of spin-flip collective
excitations.Comment: 5 pages, 3 figures, to appear in PRB Rapid Communication
Fast Incomplete Decoherence of Nuclear Spins in Quantum Hall Ferromagnet
A scenario of quantum computing process based on the manipulation of a large
number of nuclear spins in Quantum Hall (QH) ferromagnet is presented. It is
found that vacuum quantum fluctuations in the QH ferromagnetic ground state at
filling factor , associated with the virtual excitations of spin waves,
lead to fast incomplete decoherence of the nuclear spins. A fundamental upper
bound on the length of the computer memory is set by this fluctuation effect
Integer Spin Hall Effect in Ballistic Quantum Wires
We investigate the ballistic electron transport in a two dimensional Quantum
Wire under the action of an electric field (). We demonstrate how the
presence of a Spin Orbit coupling, due to the uniform electric confinement
field gives a non-commutative effect as in the presence of a transverse
magnetic field.
We discuss how the non commutation implies an edge localization of the
currents depending on the electron spins also giving a semi-classical spin
dependent Hall current.
We also discuss how it is possible obtain a quantized Spin Hall conductance
in the ballistic transport regime by developing the Landauer formalism and show
the coupling between the spin magnetic momentum and the orbital one due to the
presence of a circulating current.Comment: 7 pages, 5 figures, accepted for publication in Phys. Rev. B, PACS:
72.25.-b, 72.10.-d, 72.15.Rn, 73.23.-b, 71.10.P
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